A new version of Pentax’ 10-17mm fish-eye zoom lens with HD instead of smc coating has been leaked. It does not, sadly, seem to be a weather-sealed lens. The image released is low-resolution at current:
Update 8 July 2019: In the now-announced version of the 10-17mm fisheye lens, the hood is removable, obviating the need to shave it off when wanting to use it on a full frame body like the K-1. (You still get a “little planet” kind of image at 10mm focal length, though!)
There is, indeed, no weather sealing.
The lens will be available at the end of July for 499 USD.