Wow a lot of hullabullu about nothing on here. Pentax have a simple enough plan for their lens series. D(F)A zooms are covered at the top end with your standard range covering from 11 to 135 with f/2.8 in APS-C and 15 to 200 in FF again with f/2.8. They are reasonably expensive because f/2.8 glass costs money. So zooms covered (and they are the lens types the majority buy!)
Primes, you have 2 options, go Limited for the Pentax take on what it's engineers regard as an optic to create a pleasing image while staying true to their philosophy of smaller designs or take the DFA* line which do not have size or price constraints for high resolution bokeh
while adding micro contrast that is sometimes lacking in the Sigma designs and AF lacking in the Zeiss stuff.
Those looking for an f/4 FF series will have to wait fairly patiently. Those waiting for fast super zooms will be better off investigating another system or search for a FA* 250-600 (one sold on the UK a couple of weeks ago for circa 5K GBP. Sigma or Zeiss fans? Investigate another system.
See nice and simple.
To go back on topic, a limited wider than the 31 would be cool say a 20/4 as would something in the 105 to 120 range with apertures of f/2.5 to f/3.2 for telephoto.
Usual caveats apply in that they probably won't test the best but subject isolation and 3D pop will be in abundance.