Keep in mind that it’s not just the display panels but also the controller bridge and the DP controller + cable connector. I don’t think it’s feasible as a DIY project.
In theory they could supply a whole new ‘core’, so the package with all electronics. But in that case users would still have to open the shell themselves and it’s just so easy to damage all kind of things, get dust on lenses etc, that I’d think it would not be a good idea, Pimax would run into a lot of problems with customers.
Sending the 8k back to pimax would be possible but what would be the manufacturing cost of just the shell + lenses? It might not even be as high as the cost to ship it back to Pimax.
I think if Pimax wants to help current 8k/5k+ users out, they could just give existing users a discount.