If you read what Chris Perkins and Scott and Mike and the others have been saying, you'll discover they want the last issues of the magazines to have the focus at the moment.
This is the time to get the last issue of Dragon magazine and praise Paizo for what a good job they've done, not the time to just drop it and examine what Wizards has set up.
The folk at Wizards have posted quite a few details about what is coming up, but they're not ready to reveal the full details yet.
From what I can gather, there's going to be Dragon Online, Dungeon Online, plus other webtools, and you will be able to choose what you subscribe to.
The magazines will continue to exist, but in electronic form. You'll be able to download PDF versions of the articles and adventures, which will have some form of DRM (most likely watermarking).
Articles will come from Wizards staff and from outside submissions, just as in the days of the magazines (the submission guidelines are being worked on and will be here soon). The amount of content will be equal to or better than the days of the magazines. Personally, I wouldn't be surprised if we got an adventure a week. I'd really hope they'd do Adventure Paths, but nothing on that yet.
Gleemax itself won't be the promotional site they've got up at the moment. Speaking as someone who plays a number of different games and styles of game - RPGs, Board Games and CCGs - I'm looking forward to a site that enables me to talk about all those games together. BoardGameGeek is an amazing site, but I feel constrained that I can't talk about RPGs and CCGs there.
Cheers!