I would second something similar to Nyzul but toned to a level between ST and Coil where a group of 4 or 8 could go in and have a good time clearing areas and getting loot. The current dungeons feel a lot like a roller coaster ride to me which makes it rather exhausting to grind them cause you're always starting and stopping, but something massive that is just one big nonlinnear dungeon that you partake mainly with your static or friends could be more than fun in it's own right.

We have casual and hardcore content, but most content doesn't last too long, so lets add in content that takes a long while to work through. (Not how long it takes a party to learn a boss fight and clear it, cause if you know the fights and your party knows the fights going through all of coils doesn't take too long but content that itself is long to get through even with a competent party).