Not necessarily. Super GT cars are already roughly equal to LMP2, if not faster, while looking very much like road cars (what's underneath the surface is another thing) and they don't even have any kind of a hybrid system yet. Drop the LMP1 electronics into one of those and it will be blindingly fast for a car that still looks relatively normal.The complication of course is that a road-car based class will have to do some bizarre things to beat an LMP2 car at LeMans and remain the premier class.
Peugeot now wants in on the fun too: https://www.topgear.com/car-news/motorsport/peugeot-readying-new-hypercar-le-mans
Wonder what kind of hypercar they'll make. Will it be based on the Vision GT (we have 2 models, the original and the L500R/L750R) or something else entirely?