They said they wont make changes to Minecraft, so how will they make money?
I've seen kids wearing Minecraft backpacks and shirts, said something like "hey cool! what're you building right now?" only to discover that while they've heard of the game they haven't actually played it.
I suspect these paraphernalia stand to make a lot more money than the game does.
As far as coming out with sequels, I'm not sure how well that would work anyway. Minecraft prides itself on being extremely basic, letting the player provide the creativity. What could a sequel possibly provide that didn't do away with that premise?
Anyway. Worth 2.5 billion? Highly doubtful, especially looking at the lackluster response to anything non-Minecraft they've brought out.