It is tough, especially since the new 12.9” is shaping up to be quite a nice upgrade to the current model. Re: timing, the best source is usually Ming Chi Kuo, although it’s no guarantee. His current forecast—it’s slipped about three quarters since the initial prediction he published back in February 2019—is 3Q2020. (Personally I wouldn’t be surprised at October or November, but Kuo says July-Sept.)
There are some sources saying Q1, which Kuo had previously predicted as well, and even he hasn’t been explicitly withdrawn that earlier rumor. But as I mentioned, Kuo’s latest prediction, at least for the 12.9” Pro, is 3Q2020.
Upgrades (Kuo rumor) include mini-LED backlit display, A14X processor and 5G. Many here expect an increase in RAM from 4—>6 GB. Maybe an upgrade from 64—>128 GB for the entry level storage as well; it seems due. Quite possibly a price increase as a result of all the upgrades.
Apple is planning four to six products with mini-LED displays over the next two to three years, including a high-end 12.9-inch iPad Pro with an A14X...
www.macrumors.com