A very reliable source if mine in the club, tells me he will go to Real this summer in exchange they will send Marcelo, Bale and modric the other way and some money.
Shit is going down.
It does not make sense though.
PSG is in constant need to find money or sell players to comply with FFP but the deal you are talking about involve a very big increase of PSG wage expenses. Bale alone is on massive wages and Modric was supposed to renew for 10 M a year or something and Marcelo would want a sizable increase too.
Probably the funniest rumour i have ever heard. Also keep him mind that those deals with players being exchanged rarely happen in real life contrary to the fantasy of newspapers or fan. A rare example was Sanchez Mkhitaryan (but they were almost at the end of their contract) and Italian clubs that do it continuously.