The rumor says early 2017 will see an update to the original 12.9-inch iPad Pro as well as a new iPad mini that joins the Pro lineup. The odd part of the rumor is that the "standard" iPad Pro will get a slight bump from a 9.7-inch screen to a 10.1-inch display. But we'll believe that when we see it because it is unclear why Apple would make that change after such a long time, especially since the rumor claims the 10.1-inch iPad would be larger than the 9.7-inch iPad. It would feel more believable if we heard Apple was packing a bigger display in the same form factor by reducing bezels.
The entire iPad Pro lineup is expected to include the quad-speaker/quad-microphone setup, 3.5mm headphone jacks all around, a 12-megapixel rear camera, and True Tone display tech. Apple is also supposedly working on Smart Keyboard add-ons for each size iPad Pro.
No word on a specific date of an announcement or release, but March/April 2017 is probably a good bet.