Well, I'm currently working on my PhD in mathematics, and I'm pretty much just starting to get more serious about cubing, I'm averaging somewhere around 50 seconds but don't have time to put much work into it. But yeah, my fiancee thinks it's neat, and I plan on keeping this as a fun "sometimes" hobby for quite some time. So I think I already sort of fit "still cubing when I'm an adult". I don't really care about competitions at all, I'd just like to be as fast as I can be, I'll probably stop trying to get faster once (if) I hit 20 sec, but I'm starting to amass a good collection of different twisty puzzles, and I'll just move on to getting fast at another one of them.