I think there are a lot of factors.
I think he's going to get offensive players and/or the offense will be fine because that's him, that's what he does and he will produce offenses. I think people will want to play in that system.
On the defensive side of the ball, I think it will depend on something people really haven't discussed on here. I think it may, don't know, depend on how well he can keep the staff together.
I think one thing that has hurt Tennessee that people have not discussed is staff turnover. People have talked about that regarding the head coach. But, it has seemed like the head coach at Tennessee has lost half of his assistants every year as well.
He's got facilities, the SEC, playing time, and the chance to be a hero to sell to kids. I'm sure he can sell them on NIL opportunities as well. But, the next Tennessee team to make it to a NY6 bowl, beat Alabama, win the East, etc., will be treated like Gods.
I believe and have said for awhile that Tennessee can get it done and be "back", but it won't happen overnight and even the "right guy" is going to need some time. We all just have to see if Heupel is the right guy, but I would bet heavily he's better than Dooley, Jones, and Pruitt (I know, not saying much)