Well, you need something to move the pistons up and down now, that can handle huge stress and the full RPM of the engine. Wait... we already have that in most modern engines. And... wait, yeah, we have camshafts specifically because they allow for a much smaller mechanism that moves in only one direction, instead of moving in two directions.
Great idea, though I think it's mostly an evolution of existing camshaft/valvetrain tech being moved down to the short-block, much akin to how camshafts have mostly replaced pushrod tech in valvetrains, I think this could mostly replace rods and cranks in the lower-end. And it's really a win all around, smaller engines, easier to modify performance, smoother running, and more even torque.
Revetec hopefully won't turn into a flash-in-the-pan with the idea. It's mechanically sound as far as I can see, and could have huge wins for how smooth an engine runs, especially with how simple it makes the engine mechanically for the lower-end.