Well, Tommy is a true freshman this year. He'll redshirt (at least, I should hope so), meaning he'll be a redshirt freshman when Brion is a junior. That's plenty of distance between them. Stanton will be a true freshman next year, which means he'll be a redshirt freshman when Brion is a senior
I don't think either of them have much to do with Brion potentially being a casualty. The issue, if any exists, is if he continues to be unable to beat out Taylor. Only one year between them and I can understand Brion not wanting to wait until his senior year for a chance to start. If it's true that there's not even a competition right now and they are just shoring up all the reps for Taylor to get him up to speed...yeah, that gives us the best Taylor possible, but that is a bit of a raw deal for Brion.
If he decides to go the good soldier route I can definitely see him starting as a senior. But if he leaves, then Tommy would look at this point to be the heir apparent as a 3rd-year sophomore. Not the worst thing in the world. Got to feel pretty solid about the QB depth, for the first time in some time...