Pentax has a solid APS-C lineup. I have absolutely no misgivings about investing in a Pentax APSC-only kit. Something that was significantly missing from the lineup was a premium wide angle zoom, and lo and behold, the DA* 11-18 was recently announced. I think they've got all their bases covered now in terms of zoom. I suppose they could start making F4 versions of the F2.8 zooms. Or make a Pentax re-brand of that new Tamron super-zoom. Remake old lens designs to PLM versions seems like a cool idea as well. I means, there's still stuff for Pentax to release, but it's got all the basic stuff down now.
I've got a 20-40 Limited, so I am biased when I say Pentax has a pretty damn excellent normal zooms.
I'm never going to get rid of it. I guess what I'm trying to say is: buy premium lenses for premium results. So don't lose heart friend, you don't have to go full frame if you don't want to.