This reminds me of something....recently.
Oh, yeah, the whole Xbox live debacle.
For those unfamiliar, recently stuff hit the fan when games that were out on multiple platforms (games out on, say, the Playstation 2 and the Xbox 360). One version of those games had things like, say, a certain multiplayer mode. The Xbox version, however, didn't. Instead, you could buy the Xbox version for the same price as the other version in the store, take it home, and pay another $5 to get multiplayer mode.
The fans went wild because they suddenly realized that a company can intentionally withhold information or features, deciding to charge you more for what they once included for free.
This is similar -- if WotC withholds information that was once free so that they can charge for it, I'm going to be irked. Beyond irked -- outright angry that they'd do something so cheap. Free support is a boon to community and individual alike. You put out web enhancements, people read them, talk about them. You put out web previews, analysis of your products, etc., this keeps the buzz going for them, even after the product has been released. This added value isn't just for the product, though, it's also for the community. This will effectively splinter the community into the "haves" (the webbies who pay for this info) and the "have-nots" (those who don't).
I wonder if WotC learned from the Xbox Live scenario. They certainly seem to be trying to add value to it with the new stuff and especially the internet tabletop.
But I'd pay $5/mo for the new stuff alone. There's no reason to take away the goodies we already get for free. That's just going to kill your goodwill.