Being a dev myself I know the difficulty of this idea, but hear it out: open up the infinite forest for training simulations. Not so much new adventures as using it to rerun previous missions, even incorporate D1 content. Maybe even use the vex as recalcitrant allies against the Darkness. I'd imagine that, based on the Black Garden incident, they'd have incentive to want to help. If they can't beat us, they should have the wherewithall to help us.