I have a number of thoughts on this.
First, tanker pilots aren’t “fighting”, so they don’t need to be amazing physical specimens. What they need are excellent airmanship skills (including good formation skills). Guess what… there are plenty of fantastic pilots out there in the civilian world who could easily transition to right seat on a tanker. When the shooting starts, people will be lining up to volunteer. The air force just needs to recognize that not everyone will be 23 years old and need to start with UPT.
Second, the right seat isn’t empty… the Boomer is usually occupying the seat and (as you can probably imagine) will receive more and more training and experience as time goes on. Sure, the Boomer isn’t a “real pilot”, but (s)he obviously has the potential to be a significant resource. (The Navy has used NFOs in a similar role for decades.) So, the right seat role isn’t going away… it’s just getting merged with the Boomer role.
Yes, this is the next step on our path towards single-pilot and (eventually) autonomous airliners. We’re going to end up there one way or another, so we might as well make sure it’s done safely.