Basically I would love to see more PvE content and I know most of us would love to see legendary raids, ship raids etc etc but there's a fairly simple way to introduce more content.
Just add three more tiers to the daily challenges.
Increase difficulty and rewards. Even a single piece of rare gear dropping on the highest tier would be a great way to relieve some of the stress with the gear crunch for both players and the developers having to constantly hear about it.
The best part is that the basic framework already exists and it'd be relatively simple to add onto it.