To me it is more for those who like the strategy games. The third person/multiple plebs approach doesn't really grab me.
As for being the next hit indie game, I think they will have to start releasing now if they want to build up a fan group. Word-of-mouth (on the internet) is a large part of what made Minecraft popular. And even Notch concedes that Minecraft isn't the new way to develop and sell software. Even he considers it a once-off for the industry.