That depends. If the faster CPU is also an efficient CPU, then battery drain shouldn't be as bad. What good is a fast CPU if it's just wheels spinning in the mud? I would much prefer an efficient CPU over a fast one any day. Look at Intel's chips which has better efficiency over each generation. The newer chips can be clocked lower, use less power and still produce the same results as a higher clocked previous generation chip. Speed is not the factor, efficiency is. The more efficient the chip and architecture is the less power it should consume theoretically.
Of course, everything to deal with battery will be pure speculation at this point. Since Samsung will most likely continue using OLED screens, battery drain should be at a minimal compared to traditional LCD screens. I think RAM does need to be boosted out of necessity as well as the GPU VRAM. Especially if considering S Pen. Heat would be another issue too, right?