I'd assume they will keep the K3's body, or keep it very similar. No need to make it as big as the K-1.
My prediction is an articulating screen (K-S2 style), the K-1's AF system, Wi-Fi, improved SR, an improved 24 MP sensor with better dynamic range and high ISO performance and ... that's it. Maybe 1080/60p video instead of 1080/30p, and the better flash sync speed. The 8.3 fps burst rate is plenty and still excellent, maybe just work on reducing the slow down in AF.C. Maybe a touchscreen? The D500 has one, and it appears to be quite useful.
That's what I think
will happen, here's what I would
like to happen:
I would like to see a more improved AF system, with a wider coverage of the frame. If they add a row/column of AF points on all sides for a total of 49 points rather than the current 27 while keeping the spacing the same, we get a nice, wide coverage of the viewfinder. Not as great as the D500, but somewhere on the level of the Nikon D7200 (51 AF points) or Canon 80D (45 AF points). The K3 II was only a marginal update of the K3, so it's time for a larger one. It's AF system was a massive improvement over the K5's one, upping the AF points from 11 to 27, so we should expect a similar numerical improvement in a new K?. I also think Ricoh needs to make the jump some time from their current two-step "rough focus, stop, fine focus" method to a quicker and more precise continuous focus method found in Canon und Nikon cameras.
But can Pentax introduce a much improved AF system in an APS-C DSLR while their recent, more expensive FF flagship only gets a minor improvement? I guess it depends on when the K3 successor will be introduced. If it is only in mid-2017 and the K-1 II is already in the pipeline, they might pull it off.
Something else that I find intriguing is what Nikon did in their D500 - the camera automatically calibrates PDAF for any lens you mount. No more lengthy Siemens star shots to find out the right amount of micro adjustment. If that stuff works with various focal lengths and subject distances, it would be amazing. This feature will definitely be found in most DSLRs in the future, but can Pentax already put in in the K3 successor? Probably not, but we can dream