Another RTX3080 user here. Id say with FFXIV's current demanded you are in perfect range for 1080p. Even with what I have now it doesnt make much of a difference past 60-90 fps range, it all looks the same and feels the same. I currently play on 1440p and get around 150-200fps and notice no difference than when i played on my previous 1060.

Its all about the future proofing in todays rigs and right now isnt a good time to buy. Hold what you got but i hope you get something you enjoy in the future!