I do think a new turret or two would be fun. Not sure exactly which niches are missing, but here are a few:
A "Tesla Turret" could be different from a Lightning Turret, because it's not so much an Area Attack weapon as just something that does much more localized damage to one target, with other damage to a few smaller nearby targets. In that sense, it wouldn't be much different than the Flak Cannon already in the game, but maybe it packs a heavier punch and only hits a few units--
or even slows down their reload time for weapons? No idea how hard that would be to code, but we haven't seen any weapons that introduce any kind of "stun" effect. It'd take a little play-balancing (maybe the duration of stun is in proportion to damage done as % of a ship's total damage), but has that sort of thing been tried before?
Not the Nanite turret proposed earlier in this thread, but I love the notion of a turret that does "duration damage" where it only hits one ship at a time, but that ship will continue to take damage over the next 90 seconds (or whatever) as nanites go to work devouring the ship like termites.
Maybe a "Point Defense" turret that actually has a 50/50 chance of shooting down enemy missiles and also can do modest damage to Swarmer, Light, and Ultra-Light craft? Again, not sure how easy or hard that would be to code the "Missile defense" ability, as it's a new dynamic in the game (I think), but it'd be cool.
I wonder if there might be a way to introduce a Turret that did modest Engine Damage on top of normal damage? The Grav Turret is a nice different flavor than the Tractor Beam Turret or the Logistics Station's ability, but why not introduce a turret that actually damaged AI Engines a little bit?
Maybe even have some Turrets that could only be unlocked by Advanced Research Stations?
Can anybody else tell that, if I were an AI, I'd play a lot as "Entrenched Homeworlder"?