It’ll never happen, and this is why...
Every student pilot starts off in an ejection seat aircraft, so every student pilot will continue to get regular flight suits and wear them at their first duty station.
Plus, the fighter mafia runs the Air Force, so they will never let the one piece leave the normal rotation.
It’s all about the supply chain. Ejection seat bubbas across the US military all need to wear one piece flight suits, which means they’ll always be in the supply system. They may become a little more difficult to procure at a helo or AFSOC base, but they’ll never ever go away.
Mark my words, once they're authorized for ejection seat aircraft, we'll all be wearing them in due time. Scooter, I think they'll use your reasoning in reverse and say it's a cost savings issue and make bags go away. But it's just another move in the direction of everyone is the same.