Might wanna look up just how many watts you can get outa a gallon of jet fuel...
Combat lasers aboard aircraft will likely be powered by small fuel cartridges. They will have capacity limitations similar to cannon rounds. The cartridges will probably be single-shot and ejected from the firing mechanism when empty.
The advantage of the laser round is that it will instantly hit whatever it points towards at any visible range.
Put that in a drone craft with autonomous targeting and area-denial software, and you will have your game changer.
Of course, you can also build a ground-based laser battery that uses large, heavy capacitor banks and a steady state conventional generator for power source. That unit would have unlimited shots as long as the fuel tanks have something in them.
Another "game changer".
This century is not turning out the way that I hoped it would.