A little speculation.
When Pentax came out with K1 and 5 zoom lenses, they were expecting sales.
Sales went well, and for 1 1/2 years ago, they probably decided on more lenses.
Lenses take time to develop, so 2019 will hopefully be a year of lenses.
Many K1 owners are amateurs and many would buy DFA28-105, DFA70-200/4 probably belongs to the same style, small, WR and sharp.
A replacement for F 70-210 for travels and walks.
It seems awaited, I'll consider it as well.
I hope the DFA 50 will be included when the tests of K1II take place.
We lack wide-angle lenses, maybe Penax thinks there is manual focus lens from Samyang, so it's not so hurrying. I can consider a larger DA21 limited.
For landscap, K1II is perfect, but for example weddings, I think a faster K1S is needed.
If a K1S comes, it may be associated with DFA85 being delayed.
I'm hoping for a new roadmap for 645 at CP+
http://www.ricoh-imaging.co.jp/japan/products/lens/images/645_Mount_Lens.pdf