The N800 should be good for at least 12 months (ie. Jan 2008) and Nokia should have learned by now not to adandon it like they did the 770. I would anticipate a replacement to the N800 in maybe Q3 2008, but that's just a guess on my part - Nokia will want to get their monies worth from the N800.
However, I can (and should) pass them along the proper channel...
It will be interesting to see what others come up with as well.