After reading this story I'm struck by a bit of a parallel between Notch and Tarn Adams, the guy who writes Dwarf Fotress. Both are to be extremely passionate about the simple but massively playable games that they make, but Dwarf Fortress has a niche following and Minecraft has EXPLODED in popularity. I can see Notch riding the leviathan for a while but at some point that's got to be extremely tiring and every day's growth would take him further and further from the "I just want to sit in the basement and make fun games" that got him in the industry in the first place.
Regardless of intent, at some point if someone comes along and says "hey we'll give you $2B to walk away from this and go back to making fun games in the basement and never having to worry about money ever again" it will be a more attractive offer than trying to deal with the headache that comes with running a large company (which would be compounded by never desiring to have a large company in the first place).
Regardless of intent, at some point if someone comes along and says "hey we'll give you $2B to walk away from this and go back to making fun games in the basement and never having to worry about money ever again" it will be a more attractive offer than trying to deal with the headache that comes with running a large company (which would be compounded by never desiring to have a large company in the first place).