IMHO the technically easiest solution for a new WRC car, which could be atrractive for the current and new manufacturers, is an EV with CE working as a generator. That concept is known for more than 120 years, it works in many applications and was even used by Audi in Dakar. IMHO with well thought-out rules such cars are much easier and likely cheaper to build than the current ones. You have no gearbox, no super duper racing engine and you don't need large heavy batteries either. On top of that you have an easy way to control torque distribution even without using differentials.

Yes, it's something new and it won't sound like today's car but WRC needs something new. It badly needs something new.