Di Maria is still a solid player and he can contribute nicely to any team he goes to. He is leaving PSG soon and he is rumoured to join Juventus this summer. I think that it would be a good signing for Juventus as I believe that Di Maria can be beneficial for one or two seasons at least. Juventus want to get stronger in attacking and in their midfield also. Di Maria would be a nice addition to their wing. He might be criticized because of being 34 years old now but I don't think this would hinder him from performing good.
I think for a soccer athlete who is still under 40 years of age still has a good performance at least he can still play for the next few seasons and can give his best contribution at the end of his time because when he gets older, Maria must be able to think about old age and I think this is the end of di Maria to become a team from another club because it is impossible to move to another club with an increasing age.
Not every player can play until the age of 40. So it cannot play with maximum efficiency. Stars such as Ronaldo, Messi, Ibrahimovic can play comfortably until the age of 40. I believe that Di Maria will be among these star names. Still, it's too early to say for sure. Serie A is a tough league, high performance may be required.
We rarely see Messi, Ronaldo or Ibra out the field due to injuries. Their fitness is good enough. And I believe Messi and Ronaldo will be able to maintain their fitness and form for at least till 38/39 years. Di Maria's fitness is not bad. But I doubt if he will be good enough for a competitive league like Serie A or Premier League.