To be honest I don't think there will be that many games to be had this season. Especially not for defenders who don't tend to rotate much if they don't need to. We'll rarely have midweek games, which means less travelling, fewer injuries, more consistency in selection and fitness.
The main 3 will be Maz, De Ligt and Yoro. Maguire will compete with De Ligt, while Heaven will compete with Shaw for the backup to the LCB position until Martinez is fit. Then you have 2 of Yoro, Maz or Licha starting, 1 of them a sub and Heaven becomes injury cover.
He really won't play much this season, which is fine. He's young. I'd expect a lot more football the following season if we get back in European football. But this season will definitely be slow for a few of ours.