phrequencyviii: Yeah, I dunno about the 50$ a pop SC2 if there is going to be one every year. Doesn't that mean you have to have them all to play decent multi as well?
I might remember wrong (always a strong possibility) but I think their statement at BlizzCon was that all the multiplayer content will be available for everyone, it's just the singleplayer campaigns that will be separated into 3 boxes.
It may also that you'll be able to join in on games created with the expansions even if you don't have them but you'll only be able to play the races you've bought the box for, so you can always play terran and if you want to play zerg or protoss you'll have to buy their respective addon... as I said, fuzzy memory, but it's something close to these two possibilities.