I'd still be playing myself, honestly, except that all the servers seemed to shut down and there's like 2 servers with 1 player each and 5 bots. If/When Steam happens, I hope it'd pick back up again.
Game modes would help the most, I think. Hunter-killer style 'stealthy deathmatch' and 'Carrier Hunter' game modes would be awesome, as well as traditional 'capture the flag'. I'd also love to see things like territory control, where the teams fight to sit atop a certain location and change it to their control, maybe providing them with slow-rate healing or a few turrets that respawn.
And of course, this is Bay12. Most of us would really love to see bigger ships. Like, if these are all fighters that we're using, and some of the heavier chassis may count as 'very small warships' then being able to deploy larger ships at a high penalty would be really fun. Like something half the size of the carrier and a steep price limit. Maybe there could only be a certain number of them active per team at a time (server adjustable rules) and once one is destroyed then the next player can deploy theirs. Or give it a cooldown depending on the size. An interesting mechanic would be if spawn rate were directly tied to your ship's value, so that small, cheap ships could respawn quickly while larger vessels would be knocked out for longer. The server could have options for "x seconds to respawn" or "x% of cash-timer before respawn" so it could be set to '15 seconds per spawn' or '200% the regular timer'. That could actually encourage people to use cheaper ships instead of maxing out their value all the time.