I think that MCSG is sort of its own game, therefor won't die with the Minecraft craze.
Granted people play Normal Minecraft, along side with MCSG, but there is a huge portion of players who solely play MCSG. There's a very tight knit community surrounding this gametype, which has been active for a year and a half. A lot of us have made very close friends the time we've been here!
MCSG simply won't pull the plug, MCSG will evolve.
This game is very different from the game we all played in 1.2.5, and will continue to evolve in the coming years. Many of us will, in years, head off to college to start our lives, but we'll be replaced by a newer generation. And when they head off too college, they'll be replaced! Chad may sell, pass ownership, etc. to another party or company to continue MCSG. Mods will step down, players may leave. But all in all, this gametype, the community, the subculture will always be there, if the severs are up or not. MCSG may evolve into an MMO, MCSG may stay the same, only growing at the same pace as Minecraft itself.
Will MCSG close? No one knows, not many MMOs or large MC servers have stopped service yet. Will MCSG close in two years, or will it close in 15? Or will it just slowly slide into obscurity, when in 2225, Chad's great-great-great grandson is the single Owner/Dev/Mod for 1 US server?
I don't think MCSG will ever close because of monetary reasons, if they were in monetary danger, they wouldn't of opened 100 servers last month.
Will it go poof like MySpace?
Will it slowly slide into obscurity?
Will it reach an all-time high, and catapult?
Or will it just evolve, into something else. With the cutting edge of technology updating quickly, will MCSG even be played in PCs running Minecraft in 10 years?
All we know is that this is the community we all love, we've all had a hell of a time, we've met amazing people (not just players, but friends, commentators, artists, animators, programmers, writers, etc.), I don't think a lot of us want it to end, therefor it can't.
Long Live MCSG. <3