I would be fine with extending Maroon for 2.75 M x 3 years, but if he wants more, than I'm fine with letting him walk. It won't take long to find another player to play along side of McDavid, and maybe Puljujarvi will develop into that player.
Maroon is a good player to have on your team, but I wouldn't give him more than 3 M because I feel that the Oilers could replace him rather easily. If we signed him for over 3 M, then most likely, he will have to stay on McDavid's wing or else he might not get any points. He's a good 3rd line winger, but he shouldn't be paid as 2nd line guy.