So if Dungeon is getting smaller, you might want to check if Dragon isn't getting bigger...
This month, it's seemed like Dragon was almost entirely DM-based. My suspicion is the opposite of yours - that
Dragon didn't have enough player-oriented articles, so they put in more DM-oriented articles.
For players, there was the Monk Playtest and Celestian Order.
For DMs, there's been Game Transparency, Domains of Dread, Gontal, MM3 Playtest (yet to come), Expeditionary Dispatches, and Ampersand (DMG2).
Needless to say, as a player, I've been very disappointed with Dragon this month. All of the DM stuff (except maybe the MM3 Playtest and Ampersand) should have been Dungeon articles, and not Dragon. I was talking with my DM about it, and the basic set up now is that DMs get roughly 75% of the articles - all of Dungeon and half of Dragon. That's three times as much as the players get. Of course, that's why I think they're redistributing the articles. I think there are more players buying subscriptions now.
Really though, I think subscription should be a la carte. Pay for the parts you want, don't pay for what you don't. Of course, $10/month isn't a lot, and I just upped my subscription for a year (perfect timing on the expiration). So maybe I'm just whining hypocritically. I guess WotC is doing something right.