The reason why I don't think this is out of the question is cuz of how front-loaded the schedule is with tough opponents. If we were looking at one of our early-season "cupcake" seasons of a few decades ago, that would perhaps secure Bennie in a starter spot for the season, assuming he's impressing enough in practice to indicate he's likely to be 1 of the best 5 players on the team.
But this season is so tough early on, it puts pressure on one of Boeheim's other sensitivities: newcomer mistakes costing his teams early wins, and that consideration may very well put Jimmy in the starter spot.
The point is, you've gotta figure Bennie's gonna be a lot more "instinctive" (a lot less guessing where one of his team mates is gonna be for that pass, when to crash the boards for a rebound, etc.) as the season progresses. Now that's an assumption, but a pretty fair one IMO.
The question may--or may not--arise in January whether or not JB might wanna replace Jimmy as a starter, cuz things will be much clearer then. If Bennie's starting to make plays whenever he's in & is really starting to mesh with the other four starters, it could happen.
I can definitely see a scenario in which JB would swap Bennie's & his son's roles. The costs vs benefits could allow for it. The only problem is if BOTH Jimmy & Bennie are kicking ass when they're on the court. In that scenario, JB's tendency is to not shake things up when they're working...