I see mirrorless FF or APSC as a kind of leveling the field and (finally) allow third party and other (older and possibly resurrected names) to (re)enter the enthusiast camera market.
Compared to the complicated mirrorbox assemblies with dozens of moving parts, mirrorless has only one moving part - the shutter (ok maybe IBIS also). But the mechanical shutter can be eliminated and replaced with just an electronic one, so we could see cams with zero moving parts.
So it's a very simple box with a sensor, a mount and some computing circuitry. At that point anybody can make one, even a DIY snap together kit .. lol!
Sony has been very smart in realizing the huge profit potential with this but no doubt prices will come down with more competition. I wouldn't be too surprised to see Sigma, Tamron, Tokina etc branded cams soon along with a many other names. At some point, these things are gonna be cheap and ubiquitous like mobile phones. The lenses will be the key to any successful marketing campaign. What will differentiate each brand - lenses, features, ergonomics, UI and of course price!
So where does that leave PENTA prism X ? Let's face it, the K mount has had a long run, but the days of mechanical levers and couplings are over. The K mount along with the other ol'SLR mechanical mounts will live on mostly just in adapters. We've seen the signs over the years with the major lens brands not releasing new designs in K mount and Pentax has already put a toe into the all-electronic mounts if only with just one lens. I certainly hope that Ricoh has been working on a new system of their own. God only knows what else could they be doing all the time since they are not really releasing anything new for a long time already!