As long as they keep the no refuel rules that will be the limit to the engines!
I remember back in the turbo days and you had to manage the boost to control your fuel usage,otherwise they could run well over a 1000 hp in a 1.5 liter.... That's impressive.
I'd like to see F1 go to a anything goes but you get x amount of fuel to finish the race. Also the engine would only need to last for race weekend,none of this pansy gotta last x amount of races. Back when they used qualifying engines,that lasted maybe a dozen laps,qualifying was exciting to watch,today not so much.
Used to be F1 was the pinnacle of auto technology,these days it's all about aero and fluid dynamics. Sure with drag reduction and kers we see more passing but there's other ways to encourage that.
Will be nice to see Honda back,now all we need is for someone at Porsche to wake up!