Casemiro is said to be a target by PSG and Al-Hilal now. You know he has been quite far away from his old performances recently. This is why Manchester United are said to be thinking of parting ways with him. His time with injury didn't end up well for him. He is still a quality player but he needs to improve his effort much more than this.
When it comes to which one these teams he can go to I would say it might be Al-Hilal as they would offer a lot more money than PSG probably. But if he still wants to fight for titles in Europe then he could still choose PSG over them.
He's 31 years old now, which is not a young age. I don't know what he is aiming for at this age, whether he will follow in the footsteps of his former teammates and go to Arabia or he will stay in Europe and if Paris Saint Germain have a big interest in him that could be an option. But when going to Paris Saint Germain he must know the risks that will occur, because I see so far Paris Saint Germain has always been a graveyard for many players.
SPL is also quite competitive now, he can try if he wants to go there, especially since many European labeled players are there and that will make him quickly adapt.