I mean they can still use him to deny the Democrats a majority if the election is really close. And if it's a draw then Vance is the tie breaker vote.

He can't wont win as a republican

Actually he might depending on how the political winds blow by 2028. I can't find it now but I recently came across a graph of Fetterman's approval rating with Democrats and Republics and the former declines while the latter climbs such that the sum of the two is basically flat. He could legitimately do it. See these figures from earlier this year; he has a very respectable approval rating.

Committee chairmanships are generally given by seniority. That’s why they want octogenarian senators in safe seats: to give them control of committees.

Yes, elected in 2022, so 2028, during the big one.