I’m not waiting for one, I bought the gen 2 12.9 when it came out and have been very happy with it. What would make me buy a new one?
1. OLED display. It really is gorgeous on the iPhone X
2. FaceID
3. Reduced but not eliminated bezels allowing for a slightly larger display. I’m good with the size. If I wanted a smaller one I’d get a 10.5.
4. Gesture workflow from iPhone X
In all honesty, an OLED display alone would get me to upgrade. The other features without that probably wouldn’t.