No one knows if they'll even release an iPad Pro 2 this year. I personally think it's highly unlikely. It won't need any spec upgrades only 1 year in. I'm fairly confident that they won't release the 2 until 2017 and are shifting to a 2 year cycle on all iPads. (mini 4 + pro last year, air 3 this year, mini 5 + pro 2 next year. And so on.)
That way Pro gets the latest iPad tech first, Air gets those updates the year after and the Mini gets them the year after the Air. This seems to be what they set up for last year. The pro was all new with new tech and features, 4 speakers, screen tech, smart connector. The Mini was updated to Air 2 levels (1 year after the Air 2.) This year the air 3 looks to be getting updated to Pro tech (not quite a year after but still the same idea) 4 speakers, smart connector and still the unknown of the new screen to support the Pencil.