Well, realistically i would opt for getting the game in a presentable state for a start.
Currently with the locked out content and funny drops it can sometimes feel like playing on a bad private server lol.
So fixing what's there is what we really need as a first step for anything.
And i definetely don't think it would be a good idea to fiddle with any gameplay / shooting / balance parts.
But i also would love to have the old world back, pre-bending. I don't mind new oshur but the (galaxy) map is confusing, the old world map was
way more elegant. It's also inconsistent with the in-game messages which for example still mention empires gaining home "continent" benefits.
And second on my wishlist would be going back to old, low battle ranks. No br40 jack-of-all-trades stuff, i prefer altoholism, i mean specialization, over that.
So there you have it, just plain old regular, pre-bending world map, pre br40, current balance planetside. I bet that's a mix that would get us enough people for fun fights.
Edit: Let's be realistic though, for SOE to do this would require some serious black magic.