Minecraft has had a substantial impact on gaming in general and MMOs in specific, which means that Markus "Notch" Persson's next project is going to be watched closely by a lot of people. So it's interesting to note that in a recent interview he discusses giving 0x10c a sort of shared living space in an MMO style as well as mentioning that the game may very well charge players a regular subscription fee.
Notch freely admits that it's a matter of making money off of the game, and it's meant to be a flexible approach. If free-to-play is more palatable than a subscription model, he's willing to experiment with that as well. The interview talks extensively about keeping the game's playing field level regardless of the business model as well as potential actions in an almost-MMO space; if you're curious to see what the game might look like, head on over for all the details.