I did read that they think they have wrung all the performance they are likely to get out of the chip in the PA xX series, and that they are most likely to move to a new chip. I believe that the korg pa os is linux based, so (latency aside) it might be a straightforward process to do that, but I suspect that it (a) might be some time, during which minor updates will be made, and (b) the new product will have a different emphasis in terms of sequencer mode, but will more easily integrate with a DAW.
The MOXF series has done that, giving away a version of cubase, but I found the menus impossible to navigate (I owned a MOXF6 for three or 4 years but wanted to spend the time playing rather than programming).
And anyway, the 4X really does do everything that I am ever likely to want to do. and does it quickly.