In no way Pogba can join Real Madrid.
There are better players than him in the Real's squad right now and Pogba doesn't seem to be on the top of his form in order to play competitively. It is more possible to join Juve, but I think this is going to be a bad signing for Juventus.
This assessment is wrong imho, if you look at the two teams (Real Madrid and juventus)right now, and also taking into consideration the position Paul Pogba plays in, it's juventus that have better players suited in that role, Kroos, modric and casemiro is like all the midfielders Real have, but in juve there is pjanic, Emre Can, Rabiot, Matuidi, Ramsey and khedira who all can play CM and some of them can also play LW and this is Pogba's most preferred positions.
So I think talking about competition, it's stiffer in juve, Pogba would have to fight his way into the team, imo Madrid would be easier for him to break into, though I agree with you on the aspect of Pogba being in poor form, any team that breaks the bank to buy him, may end up regretting such action.