I don't mean immediately, but after a few years the N900 hardware wuold start to suck, and if there wouldn't be any open linux/bsd-branded devices, the last hope for us is BBX (successor from Blackberry OS and QNX, BB get nice things under roof) which is Unix-Based but mostly closed source.

but it wouldn't make impossible to have open-source-apps on top of closed-source-unix, and porting to BBX native mode should be easy, because it's ARM and it's unix-based (both like maemo)

but yeah for a year or more i wouldn't leave my N900, and when it would be too slow for me i can try overclocking etc. but the point is Nokia killed her baby...