What I'd like to see:
1. An updated version of the FA 31 Limited. With a removable hood, and maybe at least 20% smaller.
2. Something like the Canon 15-85 IS. I'm sure Pentax can make it smaller since we don't need in-lens stabilization. Great if it were WR as well, but then we've already got the 18-135 WR.. just not wide enough sometimes.
3. 135 f/2, 2.8 Prime, maybe screw-driven if necessary to make it as compact as possible
4. a DA* or WR version of the 12-24 f/4
5. Something like the Sigma 8-16mm UWA