For me.
I would like the N900 in an new package:

Big Screen > 4" with a res of 1280x768 or better
600mhz or better Dual core CPU
USB 3.0 (with OTG)
HDMI out
OS: Maemo, ubuntu etc..
with the big size due to the screen, the battery for once can be very big, the keys can be bigger or there could be more of them.

size doesn't matter for me, since this would still be better than hogging a 10" laptop around

i love my N900 since it does everything i really need in a computer/phone, and mine will get bigger with the additional homemade battery's im building + a lot of extra stuff that can fit in the mugen cover, like wireless power charging