What to expect from the 1020 Successor?

I don't own the 1020 but am interested in what improvements it will have. For my next phone I think it will be between the Z2 and the 1020 successor.

I'm guessing it will have a Snapdragon 801 or possibly the 805, a 5" 1080p Screen. What I am interested to see is if they stay with the polycarbonate design or go for a 925 approach. what do you guys think? what do current 1020 owners think needs improving?