So I am aware that good ol' CCP will add some sort of artillery most likely, where it is like the "artillery" from EVE or like a Howitzer, but what about a Calliope like turret?
Real quick, the Calliope was a variant of the M4 Sherman form WWII that had rocket pods mounted above the turret that fired rockets in a lowish arc to the target, in case you didn't know. I know that other belligerents in WWII had rocket vehicles and such, but I'll just call this suggestion the Calliope because it stands out from rocket launcher and it sounds cool.
Anyway, these tanks with the rocket pods could present another kind of artillery like turret. These would differ from a howitzer like cannon by the fact the rockets would be for mass bombardments of a large area with weak rockets. Sort of like a ground orbital strike but much weaker and much more deadly to infantry than against vehicles. Whereas the howitzer turret per say fires one big round, hits one spot, and all the damage is done in an area, where the Calliope is more spread out with its damage. This would also differ from the current missile turrets by the fact that these are arced rounds, fired up in the air and coming back down, and are long range, and have 5-20 rounds per shot not the current 4. Also, they are inaccurate, dummy rounds and couldn't fire very fast at all (low rate of fire). Their main use would be to pummel the living daylights out of a large area, and would be devastating to infantry clusters in open areas. But they would also be balanced by low ROF, dummy rounds, and buildings would be a problem by soaking up some of the rockets, making so you'd have to be closer to hit urban areas making you vulnerable.
I think it add some long range implications other than artillery, and would be a pretty spectacular rocket barrages