No one has a clue what will be in a Kindle 3 -- there aren't even any very good rumours (lots of wishlists, few credible rumours).
There's some tweaking they could do to the Kindle 2 -- some already announced like better organization. They could also update how Whispernet works. Probably they could add a sans-serif font choice.
I don't see a new model till the fall, either. Maybe they'll add WiFi as a "freenet Whispernet option". Maybe extra capacity or rethink the keyboard. But short of goign with a full colour option (and it doesn't sound like production quantities of screen technology will be available yet) all they can really do, maybe, is a Kindle 2.5 and lower the price a bit.
But there I go ... starting rumours myself!