I agree with Javier. These ideas are crazy!
The WSJ clearly needs to give up on chasing NYT readers and focus on its core business niche. The actual numbers don't matter a bit: what WSJ has to get is a total lock on the business reader.
So, of course it should be paid! (Sorry Javier, I didn't agree on that part.)
And of course, Google is not the right comparison in the same way that Martin is the wrong guy to call it: it's all about the niche! And neither Google nor Martin value niches correctly.

It's almost crazy to be pondering these ideas. Of course, it should be free.  Specially in the internet revenue will come by means of increased ads, plus the main aspect of it is whether wsj wants a.-to be a closed news provider with their views shared by a few or b.- to increase the scope of their editorial influence (hence reach or power) to a bigger audience.
b.- is a no brainer, ask google.

I agree with BJ- 2-3xing traffic will proably happen almost immediately. WSJ is a major brand, far much more so that Marketwatch, Yahoo, etc. There really isn't anything remotely comparable on the web. I buy the paper version several times a week, the only offline news I read (and I am their polar opposite politically). I won't pay for paid online content from a news source because I am an Internet marketer and not a big fan of closed gardens.
As for the affluent reader argument, even the free version is going to continue to attract a great demographic- that's their sweet spot, paid or not. My non-business friends wouldn't touch the thing, free or not.

BJ: Exactly part of what I was saying in my analysis, to which Rafat links above. (Not sure if I'm "everybody" or "their mother" ;) .) Subscription revenue is more solid, better for cash flow, less susceptible to economic swing, and hard to replace.

Also, unlike Lehman—whose analysis is sophisticated and good—I purposely did NOT include Marketwatch, which is already free and available and (according to reports earlier this year) close to sold out; it's not clear making WSJ free would have much of an effect on Marketwatch—though the rising traffic would probably lift Marketwatch, as well, at least somewhat.

This free WSJ scenario analysis is a bit simplistic. WSJ commands higher CPMs than the Times in part because the paid model attracts a very affluent, serious business audience. YOu open it up, and the incremental audience will not be as affluent. The increase in traffic of 2-3x isn't outrageous however. With a little SEO and some promotion, it really shouldn't be all that tough. It has almost double the circulation of the Times after all and is considered the authority for business. CNN? Money? Yahoo? are these really the brands you think of when you think business?  I don't know what the net result would be of going free, but unlike other paid sites - TimesSelect, for example - people can expense their WSJ.com subscription and they have a lot of bulk business/site license type subscriptions. So there's an added price insensitivity to the subscription price that other consumer sites can't match. If your company's footing the bill, you'll happily pay the $100 a year.  But who expects equity research analysts to have nuanced views of consumer behavior and advertising dynamics?