The FIA has suggested the 2020 cars return to more of a GTP regulations (such as http://tech-racingcars.wikidot.com/mercedes-clr). The cars will be bigger with 2 seats in the cockpit, spec hybrid system in the front, and up to ~520-550hp from the engine). And also to have 1/4 budget of the current LMP1 factory effort.
http://sportscar365.com/lemans/wec/details-of-2020-hypercar-design-revealed/