Uuuhm... did you see the most recent commercial for the N900? If Nokia internally works like that, geeeez, the answer to that last question will be "No!"...

Ok, seriously, no they won't of course change as drastically as they did from OS2008 to Maemo 5. *BUT* I do think the N900 will be abandoned upon the presentation of the next gen Nxxx. Transition from the niche and experimental test bed onto consumer land most likely also means a change in marketing technique, eg. marketing behaviour which has to be considered normal in mass markets. Abandoning previous device generations *is* perfectly normal in electronical gadget mass markets. And it's not like they didn't try before with the 770 and the N800.