It all depends what happens with Akanji. Zorc said yesterday that they are still assessing him. If he's out for a significant amount of time, Balerdi will see the bench some games, and might even play a game or two. He'd be at least 4th, and could be 3rd if he shows well and they consider his price tag to move him ahead of Toprak. Diallo also plays at LB at times, so there is a chance Balerdi could get into the team a little more regularly, but its probably not going to happen anytime soon.
Our top 3 CB's are all really good. I figure one or two of them will get sold within a season or two, so that might be when Balerdi gets more of a regular chance. I could also see him move ahead of Toprak for next season, regardless, so I don't think he's looking at no minutes when everyone's healthy, but it'll be hard to break in. For the time being, it could be a little easier, depending on Akanji's injury.