Cave/bunker exploration with semi-claustrophobic corridors. There's a lot of terrain verticality shown in the new footage that should be put to good use. Speaking of verticality, the massive enemies might require air movement, so I'd nominate Gunvalkyrie as an optimal skill-based movement system.
Tweaked story progression. As I mentioned in another thread, the very disjointed feeling I'm getting now for the main story could be alleviated by reintroducing the scattered quest markers on the field, but leaving the rather wonky Matter Board system. Also dotting the landscape could be quest giver stations, so that returning to the main base/ship won't be immediately necessary for a new assignment.
Chao Garden, naturally.
MAG utility: Need extra storage? Upgrade your MAG for storage; trade-off for other functionality of course.
Converse with fellow players