I think a 32-player PvE zombie mode using the existing Conquest maps could be really fun.

Instead of regular waves, zombies could actively overrun objectives and take control of different parts of the map, forcing the team to regroup and recapture lost sectors. Different zombie types could add more variety, with basic hordes, faster infected, tougher enemies, and special types that threaten infantry or vehicles differently.

The full vehicle system could still be used, but adding limited fuel would create another layer of strategy. Players would have to manage fuel, ammunition, repairs, and positioning while trying to keep the map under control. It could lead to some really memorable situations, like mowing down a horde from a helicopter only to run low on fuel while you're still directly over hundreds of zombies.

Basically, a large-scale combined-arms survival mode where 32 players work together to stop the map from gradually being overwhelmed.