Going forward, I think the K-S1 will settle in to the entry-level slot at around $500. IMHO, the K-50 and K-3 are fine as-is but as has been mentioned they seem to be dropping in price and due (time-wise) for replacement. Then there's the potential FF to deal with. I can't see Pentax coming out with three brand new models in the next six months though, not to mention the lenses that would be needed for the FF.
The K-50 is at $350 body only. That's an insane deal and qualifies as closeout pricing to me, similar to when the K-5IIs was going for $500 or whatever before it was discontinued. It's older than the K-3...maybe they'll replace that one first, putting in the 20mp AA-less sensor from the K-S1 and whatever other goodies they have.
I can't see a K-3 replacement coming out within 6 months either direction of a potential FF. For example, I would see either a K-3II at CP+ followed by a FF next fall, or vice versa. Unfortunately, if I were in charge of sales/marketing at Ricoh, I would put the K-3II out first to reap sales to the Pentax faithful, then hit them with the FF they can't resist 6 months later.
All speculation, obviously. In my opinion, the K-3 is good for another year, and the only thing wrong with the K-50 is that the K-S1 has more MPs and the AA-less design. But with the K-3 currently selling for $800, where do you price the K-50II?