Tesla superchargers are delivering 250 kW today, at ~380V. The largest of these is like 40 stalls; they are not shared (you're thinking of the 150 kW v2 chargers that split current between two stalls). Hyundai is about to ship a car that can take current at 800V. (There are 350 kW CCS chargers too, though those seem to be poorly exploited and hard to measure in practice with real cars; but I've watched my Model Y sink 250 kW with my own eyes.)

So just naive application of already-deployed technology can get you to ~500 kW. You don't think someone's going to squeeze out a thicker cable, really? No, this is doable. The real limit is how much current the battery can sink without degradation at the top end of the charge curve. The electrical stuff is kinda trivial.