If FFXIV is dedicated to reducing FOMO I don't see why it shouldn't be available for future players once they add Replica names. I mean, they did say in a LL they'd bring back past season PVP rewards in the future maybe even 7.2.
TBH I've been playing since 2014 and I've never seen anyone wear the old PVP sets in town or in dungeons so I feel like old owners wouldn't care at all along with old mounts.
