All 4- and 8-man old content can now be run unsynced, and while some fights can still be annoying (Titan, Leviathan etc. with insta-death mechanics), they have the ability to be run with a few friends so you can get whatever you're after.

The content I see a lot of people asking to be made some kind of relevant again is Crystal Tower - it still requires 24 people to want to do it, can't be unsynced, and is in general just realistically impossible to get into.

My personal preference for solving that particular issue is a CT Roulette, let it award a few tomestones of Law and Esoterics, and just let it be an alternative method for capping your tomestones compared to running the same two Expert dungeons again and again and again.