I'd say the biggest problem with getting their customers to stay with them and upgrade to the next tablet is simply that there's much more choice out there and people who've had n800 and n810's are now getting eager to upgrade and they might not wait.

II might even go so far as to say that the n800 and n810 are so well understood and their limits reached that they're in danger of becoming stale, and being out of production means less "fresh blood" to bring new and crazy ideas. Take a look at the Zaurus community: still lots of talented people, still interested in new stuff, but there's nothing particularly new happening and people are bored.