Tesla Semi has multiple packs that can be charged in parallel. The Megacharger will (likely) be 4 Superchargers combined. 1MW should be enough ;)

re: announcement, I'm surprised not much has been said about the flagship cars (S/X). With their current battery architecture (using 18650 batteries), they're not capable of 250kW charge rates. I wonder if they have recently updated them to new 2170 battery packs or if they're going to do that soon.