I can assume that Pogba's location will depend on whether Real Madrid can conclude a contract with Mbappe and Haaland at the same time. If yes, then this opens the door to PSG, if not, then Pogba will be a good replacement for Modric, who, in any case, will not be able to play in Real for more than one or two seasons.
I read few days ago that Haaland is not interested in joining Real Madrid if Mbappe is there since he won't be able to shine so he prefer in that case Barcelona so they will reproduce the CR7 - Messi phenomenon.
For Pogba he will be a free agent and every team will accept him in if they will be able to afford his salary. I think he will play for Real Madrid or PSG next season. For Modric, he is still a key player in Real Madrid and Ancelotti will keep him for a while unless he won't be able to add anything to the club.
This information about Haaland seems dubious to me. Firstly, I do not think that Haaland considers himself to be worse than Mbappe (and he has every reason for that, since Haaland reveals his potential much better than Mbappe). Secondly, even if Haaland is afraid of competition with Mbappe, how did the journalists find out about it? I'm sure Haaland will never say this out loud, even if it is true.