Grundstrom, Engvall and even Brooks will be NHL ready come next fall. I'd even toss Jeremy Bracco in there, though that largely depends on his AHL production this year. So while it's easy to say that Brown only makes 2.1M, if he's on the 4th line (assuming our top 9 remains Marleau, Matthews, Nylander, Hyman, Tavares, Marner, Johnsson, Kadri, Kapanen) and we could put Engvall in that spot for 925K, that's essentially 1.2M we saved.
The nice thing is, I believe we avoided having to put Horton on LTIR this year, so the rookie bonuses will be cleared, so we'll be able to use the LTIR next season if necessary.
So say we trade Connor Brown somewhere;
Patrick Marleau ($6.25M) - Auston Matthews ($11M) - William Nylander ($7M)
Zach Hyman ($2.25M) - John Tavares ($11M) - Mitch Marner ($8M)
Andreas Johnsson ($2M) - Nazem Kadri (4.5M) - Kasper Kapanen ($2M)
Carl Grundstrom ($925K) - Par Lindholm (1M) - Pierre Engvall ($925K)
Frederik Gauthier/Other ($1M)
Total Forwards: $57.85M
Morgan Rielly ($4.5M) - Nikita Zaitsev ($4.5M)
Jake Gardiner ($6M) - Timothy Liljegren ($900K)
Travis Dermott ($850K) - Igor Ozhiganov ($1.2M)
Calle Rosen ($900K) - Andreas Borgman ($900K)
Total Defense: $19.75M
Frederik Andersen ($5.5M) - McBackup/Sparks/Pickard ($900K)
Total Goalies: $6.4M
Total Salary: 84M
LTIR Allowance: (5.3M)
Total Cap Hit: 78.7M
So based on this years cap, we have roughly 800K for any salary increases above what I have listed. Then you'll need to add whatever the cap increases for next season. So it's still possible we can keep Connor Brown as well. All depends on the cap increase.