The nerf I've been planning is to extend the "can't build core (X) turret on same planet as non-core (X) turret" (where X is needler, laser, etc) to "can't build any core turret on same planet as any non-core turret (that has a core variant, so leaving grav/tractor/etc out of this)".
So, you'll be removing Core Lightning and Core Flak turrets from the game?
At least, in practice. As a serious matter, I cannot imagine using those unless I'd already captured Core Missile or Core Sniper controllers.
If none of my previous ideas work, maybe the radical answer is to change all the turrets to be per planet caps. Lower the caps on them and just let people build everything everywhere.
The idea of lowering turret caps and making them per-planet has certainly come up before, but the "lowering caps" part is simply intolerable to too many people here.
Even with Core Turrets in the 6.044 Overpowered state, Exowaves will still roll right over them. That sort of AI firepower is why chokepoints are basically a requirement. If the chokepoint is eliminated by making all defenses distributed, then something needs to be done to balance the Ai response to the current fortifications.
Although, playing with Core Turrets has put me significantly more in favor of the 'distributed defense in-depth' idea. I just think it'll be a huge rebalance, along the same order of effort as the Armor rework. But I'm leaning more in favor of it that the pro-chokepoint view I used to hold.