If Ronald Leary gets demoted and is able to learn C, there wouldn't be any need to dress Mackenzy Bernadeau for games.
But Leary has never practiced a snap as a pivot as far as I'm aware. I think he would've cross-trained there by now if deemed capable (maybe he has and I don't remember).
Darrion Weems would be practicing as the swing tackle, he'd be the most prepared to take over for an injured OT.
The starting guards, most especially if it includes rookie La'el Collins, are going to be taking snaps solely on the inside. Collins has never played on the right side of the line, it can be a very steep learning curve. Some NFL players can't do it.
Zack Martin did get some work last year at center, but it's an inside position, there were no reports of him taking a single snap outside at tackle. He needed to focus on becoming an inside player, I feel the same will hold true for Collins, if that's where he lands.
The best seven players doesn't necessarily make them the best seven to dress for games.
The reserves have to bring some flexibility and often help on specials.
Starting five, swing tackle, swing interior.