What do people want to spend gold on at higher levels?
Previous editions had the magic item supermarket to sink gold into. 3E let you get them half price with the right feat and a little XP loss.
Domain management doesn't seem popular and doesn't fit a lot of campaigns which don't have extended periods of downtime. The only published adventure I've played or run that has the time between adventures for it was running Kingmaker, which is kind of the whole point of the campaign.
I'd like to be able to spend money on something because I don't think the treasure hoard is going to go away.
I'd rather get some kind of boon for completing high level adventures, to be honest. Absorb part of a dragons power for slaying it instead of dealing with 2000gp, 5000sp, 20,000cp and miscellaneous art objects and gems.
I've tried several options & written a couple things for it, but really a big problem stems from 5e thwarting it by not having enough headspace within the design to have items that are slightly better or differently better so you wind up with a system the players might use once or twice & then are not likely to use the rest of the campaign.

I suppose the answer in the end will depend on what sort of designspace gets added to weapons/armor/gear