I think Kerfoot (or they trade him and replace with a different guy similar $) and Robertson on the top lines make a lot of sense personally. AM + MM get paid exhorbonent amounts - they need to carry their line with a cheap player that has some talent. Could put Galchenyuk in that spot if you want if Robertson shows at camp hes not ready at all.
Robertson - Matthews - Marner
Kerfoot - Tavares - Nylander
Mikheyev - XXX - XXX
Engvall - Spezza - Simmonds
Assume 3M to the 1B goalie and you have about 6 million to fill out this third line with players that are better than Engvall and make Mikheyev the worst player on the third line (I think Mikheyev is fine on the third line so long as hes the worst player of the 3).
Seravelli mentioned that Foligno could come back. I wouldn't hate Foligno at 2M + Granlund at 4M for 1 year. Gives them two guys that can play C, move around the lineup (Kefoot has shown he can move around as well).
Its not perfect at all, but I think the way this team gets better is by putting the core 4 on their own islands, carrying some skill - and allocating the rest of the money (after setting up the 1B goalie) to L3.
The other thing is... they can accrue cap space and get a rental at the deadline to help the top six if Robertson shows he can't handle it during the year. Just don't trade for Foligno next year, get the Hall type guy.