The Lightning will have to make some tough decisions this summer. Stamkos walking is probably the most likely outcome but if not... Cirelli and Černák are very interesting names
So, their D and G are set with Sergachev healthy.
They have 11.5M in cap space with 9 forwards, 5D and 1 G
I think you can make the space needed rather easy.
Buyout Sheary, saves 1.5M this year and 1M the year after, so 13M
Move Jeannot, that's 2.6M freed.
You are now at 15.5M with 7 forwards, 5D, 1G.
So that really leaves: What to do with Stamkos. Practically, he's 34. But, he hasn't dropped off as much as typical for the aging curve, and he's won two cups and been to 4 finals as the teams captain. So there is a loyalty there.
You have two forwards without trade protection, and that is Hagel and Cirelli. It'll be harder to replace Cirelli and he's a home grown talent. Hagel is probably the no brainer to move on, even though he's been very productive. He'll net a decent return and you can probably get a ELC winger back and draft capital.