I believe there is an "endless" version of either Blockade or Search & Destroy in Dev App. It would be neat if this was employed in the actual game.
This would require some modification to existing mechanics, but it could also be interesting to have a game mode similar to this where each ship only has one life, and when it is destroyed the players enter a spectate mode. After the fleet is destroyed, it's game over. There wouldn't be a base to defend, which would make running for your life a viable strategy until you're completely overrun.
A mode similar to Infiltration - where your goal is to get as many ships as possible to the end point across the map - could also be fun.