based on what?

Then why would he extend?

oh, I wrote that as a hypothetical. doesn't have to be right now, but if Buffalo isn't good in 2 years then what reason would he have to stay

Hypothetically, even if he did want out, the Sabres would want more. Even if he isn't at top potential in a couple years, they'll probably charge roughly the same amount as they would for an injured eichel. So I think you'd have to throw in a bit more.

Not close and he wouldnt sign a deal and then want out the same year so your going to have to do some projection, to like 23-24, for this to even make sense

Buffalo would want more for Dahlin. Turcotte and/or Clarke to start.

I betcha on virtually all teams, there are about five players that want out. In a case where the team or organization sucks, the number is much higher. Dahlin knows he is stuck in Buffalo for a total seven years once he signed his first contract. Just play the best you can, shut your mouth and be a UFA at age 26, then sign elsewhere.