Off the top of my head:

Unreal should be expanded to Savage. The game has a backlog of excellent encounter designs that are simply collecting dust. Syncing them isn't really adequate or incentivized.

Variant/Criterion style systems should be improved and expanded. Introduce a weekly bounty system that rotates through various routes each week. Introduce internal progression to this system via something like content specific gear and logos actions, and design the various routes to incentivize the use of varied loadouts. This content would be a good spot to stick catch-up gear with a unique appearance.

Ultimate should be adjusted to release alongside the first and final raid tier of an expansion, instead of the first and second.

Field content ala Bozja/Eureka should return, ideally as a combination of the best things learned from both. Personally I would like to see a return of the danger and sense of progression from Eureka, but with the better designed Bozja style boss encounters and duties.