Your guessing he isn’t going to be as patient as Ole, Rangnick, and Southgate for that matter have all been with him. We don’t know that. dropping a captain is a huge deal with most managers only do as a last resort.
Plus he may not have much choice not of our others defenders are these blinding beacons of hope, Varane was injury prone and patchy when he played. And let’s not forget we paid a world record fee for Maguire because players like Bailly, Lindelof and Jones we’re struggling.
So the likely hood is Maguire starts most games at least next season.
You're overrating the captain aspect. Maguire isn't really a bigger name than Rooney when he was dropped to the bench while being United's captain during his last season.
Maguire is a nobody when it comes to United and even among United's captains history and no manager is going to persist with him while he's costing the team just because he's wearing the armband or because he costed a lot.
The only logical thing in your post is if he has no other options than him but the armband or his fee isn't something a foreign manager like Ten Hag will care about. Again, Maguire isn't a bigger name than Rooney.
He'll be starter at the start of the season but only his form will determine what will happen next.