IMO the only real way to solve this is a weird way: Two or three tiers of PVP gear that release with new phases. When you hit R14 once, you have access to them forever.
I don’t think the ideas of “Make PVP gear unusable in PVE” would ever be workable though.
Assuming any kind of shift is made, it will be immediately after the change is implemented and probably last for a few months before things return to whatever is normal for each cluster. It will be short lived because a) R14 is permanent, the clusters have been P6 for a really long time now and the servers arent shutting down any time soon.
Edit: To more accurately answer the question the only change I can foresee is more BGs being run which may have an indeterminable impact on the number of MCs being run for the short term but people who play Era for the sake of playing Era at worse might end up doing MC/BWL in R14 gear. Whole 40 man raids arent going to be comprised of nothing but R14s though.