I would expect the same with the new M3 that for the wheel horsepower gains on the F80 to exceed the crank horsepower difference presented by BMW between the F80 and the E90 M3's. This power increase combined with a claimed weight loss by 220 pounds would make for an M3 that performs very well.
The thing is, 220 pounds is a lot to shave off the F30. And if the F80 M3 undercuts the E90 M3 by 220 pounds that means it would weigh somewhere in the 33XX pound range. Owners have weighed their E92/E90 M3's in the 35XX pound range. Confusion arises that the E9X is heavy because BMW lists its European weight which includes a 75kg driver.
BMW claims the current F30 335i weighs 3555 pounds. So, about what an E92 M3 weighs. That would mean if the rumor for 100 kg weight loss were correct the F80 M3 would undercut the F30 335i and E92 M3 by 220 pounds. That means weight less than an E46 M3 as well, not happening. What is more likely is that BMW will undercut the 3704 pound curb weight they provide for the E92 M3 putting the F80 M3 somewhere in the 35XX pound range or just about the exact same as the E90/E92.
We will find out soon enough with the car expected at the Los Angeles Auto Show in November.