No one knows when the next Maemo device will be out or if the N900 will be upgradable or to what extent. This section is for posts about the N900 hardware and not pointless speculation on the next device or firmware.
"Hardware-specific discussion about the fourth generation of Internet Tablets."
So the OP is both pointless and in the wrong section. The more appropriate place is the OS/Platform area.

Personally I do not understand people asking if they should buy a device now or wait for the next one. If you cannot make that decision yourself then I very much doubt the N900 is for you.