If we go max term, that is 8 years with a 5 RFA/3UFA split.
If you look at comp's from the last few years who were a similar age and got 7-8 year deals, your pool of comp's is kind of small.
You have basically RNH, Ehlers, Scheifele, Monahan, Landeskog, and Mackinnon.
All of these guys got between 5.5 mil - 6.3 million. The guys who got more than 6 mil all had a better track record than Larkin does at the moment.
I would guess 8 years x ~6.00 million for Larkin if we were to go max term.
Ehlers is the best comp for him. Ehlers had 102 pts in 154 games, for .66 PPG. Larkin is currently at .58 PPG. But with Ehlers they went 7 years as opposed to 8. That extra year of UFA, plus the fact that Larkin plays center probably off sets that and puts them at about an equal cap hit.