Would be a massive mistake for them, and although I thought he was poor today, in general this season he's been very good.
Transfer's like Mbappé and Neymar do not come along very often. In the short term, they've got an unbalanced squad and an embarrassing loss here, but mid to long term, they can get in a great defensive mid and pair of fullbacks and they'll be an incredible side under the right management.
I don't think they'll struggle too much with the Mbappé money as they do have a bunch of high value assets. Goncalo Guedes has been one of the stand out players in Spain this season when fit, he was the main reason Valencia were ahead of Real and Atletico up to Christmas before his injury, and PSG could easily recoup €50m+ for his sale.
Draxler would have a lot of suitors for similar money, Krychowiak will probably get picked up by a premier league side for 15m or so, Jese similar. They've got a fair bit of dead wood to offload.
It shouldn't be that much of a stretch for them to come up with the Mbappé money in incoming fees.