The thing is, even if Ricoh releases a K-3II replacement imminently, it's going to be lot more expensive... somewhere between the pricing of the KP and the K-1. That makes the K-3II something of a bargain, even considering its age. Plus, if you disregard the release date and simply look at its capabilities, it's still a very competitive model in terms of performance and features including pixel-shift mode, AA filter simulation, GPS, astro-tracking, dual card slots, high burst rate and good buffer size, heavy-duty all-weather construction etc. Frankly, it's as much of a monster now as it was when released, and most photographers will never use half of its capabilities, let alone stretch them.
More-recent models like the K-70 and KP offer better high ISO performance, but unless you really expect to be shooting at very high ISO levels most of the time (and I'd suggest that's unlikely, unless you're doing a lot of indoor sports and/or concert photography, for example), that really is immaterial. For many photographers, the majority of everyday shooting is likely to be at ISO 100 - 1600, where the K-3II performs incredibly well. And, with a little bit of post-processing, you can confidently shoot it at ISO 6400 and higher depending on the application.
If your K-50 is still serving you well and you have no immediate need to upgrade, I'd suggest waiting 6 - 12 months just to see what Ricoh releases next. My guess is, though, the next model won't be cheap, and discounts on the K-3II at close-out are unlikely to be huge as a result. If the discounts
are huge, I'll be getting another K-3II and retiring my K-3