It does seem like an odd move to me. I don't think it'll work.
1) Free websites which move to a pay model, historically, tend to fail. This isn't an absolute (ther eare some success stories), but if it works, it'll be bucking a trend.
2) The user base of Wizards.com is much, much younger than here. And I'm assuming that a credit card will be needed to access this material.
3) Outside of their own site, their customer base will be the same as RPGNow/DTRPG (now OBS). The pay-for-D&D-stuff-online market is saturated. Their advantage is that their stuff is official, but outside of thier own existing traffic, I'm not convinced that's a strong enough draw (those who eagery gobble up everything official are already there).
I might be proved wrong. We'll see. But if they'd asked me (which they wouldn't, of course, but if they had), I'd have advised against it.