Just based on some trends, here are my predictions for the iPad 3. (Let me be clear, I am talking about the 2012 rev to the iPad 2 that just came out... Not a hypothetical 7" iPad 3 some are predicting for fall 2011.)
Lighter (more pleasure to hold... Crucial in a handheld... This enabled by better batteries)
Not thinner (iPad 2 is about as thin as you would want it to be)
Much better rear-facing camera
12 hour battery life
Does not run flash
LTE and GSM - no CDMA version
No silver bezel visible from the front at all
Finally an updated native calendar app.
Double the storage capacity, similar/same price
Some kind of seamless device-to-device communication... Your iPhone, iPad, and your friend/wife's iPhone should all be able to communicate for games, etc with zero hassle. Current implementations are just too futzy.
I will want one
Retina display (I am on the fence on this currently... Certainly Apple has invested heavily in display tech, but this just may not yet be feasible economically in early 2012... But boy oh boy would it sure make people want to upgrade!)
No haptic display; though I would love that.
- Scuba Steve