I expect Amazon to accelerate at least one more development because of the competition coming to market. My prediction is something late in the year, in time for Xmas 2010.
But I've got no good forecast of what changes it'll have. Could easily use the Nook dual-screen. A lot of folks find that a cool idea. I'm hoping for a bump in E-ink contrast and maybe resolution. A touchscreen will be disappointing if it lowers contrast (like the Sonys). Straight wifi transfers would be nice but I'm not expecting that from Amazon since that doesn't help lock in readers to their store. So who knows?