Mbappe and Dybala both has contracts expiring in 2022. I think it'd be a fair swap tbh
Still, swapping Dybala+Ronaldo for Mbappe is a major loss for PSG, those 2 won't have any resale value, the on pitch contribution might improve in short-term (if Dybala manages to stay fit), but will suffer long-term and their wage bill will grow considerably. Only contributing factor for them would be the hype that Ronaldo generates, but I don't think it's enough to outweigh all the negatives.
I'd give up literally any player we have for Mbappe, he's that good.
