In a survey of technology experts and stakeholders, conducted by the Pew Research Center’s Internet & American Life Project and Elon University’s Imagining the Internet Center, 65 percent of people said they believe that mobile payment technology will be widespread by 2020.

Meanwhile, it found a dissenting view, with 33 percent of those same stakeholders believing it will take longer because people will resist technology that wants to learn everything about their personal purchasing habits.

Relatively few people believed that cash or credit cards will disappear entirely.

It’s unclear whether the 2020 date is optimistic or seems too far out given that so many companies are investing aggressively today. PayPal and Google are the two most notable technology companies going after the opportunity, but so are the incumbents, including Visa, MasterCard and American Express. Additionally, the U.S. wireless carriers are mapping out their own plans through a joint venture called Isis.

As part of the report, Pew published remarks from a few respondents:

Google’s Chief Economist Hal Varian said: “The 2020 date might be a bit optimistic, but I’m sure that this will happen. What is in your wallet now? Identification, payment, and personal items. All this will easily fit in your mobile device and will inevitably do so.”

Susan Crawford, professor at Harvard’s Kennedy School of Government, put it more practically: “There is nothing more imaginary than a monetary system. … Of course we’ll move to even more abstract representations of value. Other countries are already content to use their phones; we’ll catch up eventually.”

That’s the conclusion of a new survey by the Pew Research Center’s Internet & American Life Project that found a majority of tech-savvy folks believe they won’t be doing nearly so much work on the desktop a decade from now. Seventy-one percent of the 900 “technology experts and stakeholders” Pew interviewed agreed with the following statement:

“By 2020, most people won’t do their work with software running on a general-purpose PC. Instead, they will work in Internet-based applications such as Google Docs, and in applications run from smartphones. Aspiring application developers will develop for smartphone vendors and companies that provide Internet-based applications, because most innovative work will be done in that domain, instead of designing applications that run on a PC operating system.”

Given the growing enthusiasm for cloud-based social networking services (Twitter, Facebook), cloud-based entertainment services (Hulu, YouTube, Pandora) and cloud-based productivity suites (Zoho, Google Docs and the latest version of Microsoft Office), this doesn’t seem like a particularly aggressive prediction.

Clearly, though, there are some obstacles to be overcome. Privacy and security are, and will continue to be, big issues here, as is bandwidth. But once they’re resolved, the division between “cloud computing” and “computing” as we think of it today will likely be gone, as Google’s (GOOG) chief economist, Hal Varian notes. “In the future we will neither know, nor care where our data resides,” he said. “In fact, our data will be distributed in the cloud, where it can be accessed any time, any place, on any device, by any authorized user.”

Yesterday, BoomTown took a rather strong stand against Google and its recent aggressive efforts to defend its outsourcing deal to sell some of Yahoo’s search advertising.

Given that the pair have a more than 80 percent combined market share in the search business, I and many others–advertisers, publishers and state and federal regulators–are a bit nervous about further concentration of market power in one set of hands, even if they are such Googley hands.

But in the interest of fairness and because I like to argue with myself–combined with some insights from some smart people I have kibitzed with on the issue–here is a counterpoint with three key reasons why Google and Yahoo might hold firm in launching the partnership, which sources said is likely to start on Oct. 9.

1.) The Justice Department is not actually serious about taking on Google.

While it is true that the government has hired seasoned litigator Sandy Litvack–the former antitrust chief in the Jimmy Carter administration–to consider whether it has a case against the controversial partnership, the move by the DOJ’s antitrust unit might be more political coverage than anything else.

Assistant Attorney General for Antitrust Thomas Barnett (pictured here), who will likely be leaving that post after the November election, has not been much of a trustbuster, to say the least, taking a mostly hands-off attitude toward business regulation.

Thus, he might be making the move to placate intense lobbying by Microsoft (MSFT) and to look like the DOJ’s antitrust unit can act.

Interestingly, Barnett had, according to a New York Times piece last year, “urged state prosecutors to reject a confidential antitrust complaint filed by Google that is tied to a consent decree that monitors Microsoft’s behavior. Google has accused Microsoft of designing its latest operating system, Vista, to discourage the use of Google’s desktop search program.”

And even more interesting, Barnett previously worked for a law firm that repped Microsoft on antitrust issues (although Barnett did not work on Microsoft cases).

2.) The Justice Department will lose if it decides to make a case against Google.

Let’s be clear–Google (GOOG) has done nothing wrong yet, because the Yahoo deal has not yet begun.

Well, except that it has been scarily successful in its primary business of search.

Google has argued that such success is no crime and that the deal would have strong user benefits.

The company has also argued that working with Yahoo (YHOO) will not raise online ad prices, part of Google’s basic argument that its auction-style business model where advertisers set the price makes that impossible.

But what its critics are essentially asserting is that, because of its dominance, Google should simply not be allowed to strike a partnership with the second largest player, Yahoo.

Fears include that rise in online ad prices, a Google control over the market that would make it impossible for others to compete and an increased ability to dictate terms to customers.

But, Google argues, that’s all speculative and unknowable until the partnership with Yahoo launches.

Thus, there’s not a whole lot for the Justice Department to hang a case on, in contrast to its case against Microsoft, which landed in court because of bullying behavior that actually took place before the case was waged.

So why should Google run away, when there is no tangible proof of abuse?

Better still, if the DOJ did take Google on and Google won, the Justice Department would be hard-pressed to come at Google again for a good long time.

3.) If Google caves and walks away, it damages Yahoo and makes for a bad precedent.

It is not likely that Google wants to make an enemy of Yahoo, because even in its weakened state, Yahoo is a better to have as a friend than as a foe.

And taking away an expected $800 million Yahoo estimates it will make in added revenue on the deal is not any way to treat a friend.

In addition, one could argue that walking away now is premature. As Google’s power grows, there will never be a better chance for it to win its arguments.

And if Google gives in to DOJ pressure now, essentially admitting it is too powerful, it might have to concede one thing after the next in the future–from distribution deals to acquisitions to whatever it might try to do.

Finally, while I still believe Google should not be in business with Yahoo, I think it is indeed going to stick to its typically stubborn guns, launch on Oct. 9 and then make tweaks that regulators might request based on how the partnership goes.

But, in order to do that most smoothly, it might be a good idea for Google execs to stop making so much noise defending themselves and to resist the urge to attack Microsoft so loudly.

It might even take a clue from the unusually quiet Yahoo, from whom not a peep has been heard on the issue.

Google could do with some of that self-control.

Because that famous line from “Hamlet” certainly applies: The search giant doth protest too much, methinks.

(By the way, besides a press conference by CEO Eric Schmidt this week on the Yahoogle deal, here are two Google posts defending the deal on its public policy blog. One is by Google Chief Economist Hal Varian and another by U.S. ad head Tim Armstrong.

Please see this disclosure related to me and Google.