Let me take a more exact crack at this...
Carter 2.525M - 895K = 1.63
Feje = 1.88
Shaheen = .96, (has a dead cap hit of 333K)
So these three generate about 4.5M. We still need at least this much to even get Armstead in the door. ...and I agree that Shaheen and at least one of these two are dead men walking, so no disagreement thus far.
Gaskin at 2.5 would generate 1.6M, and again, I don't disagree with you about losing him.
Cutting all four would probably pay for Tretter, but would still leave us unable to get Armstead in the building. Rather, I think we have to cut all four to get Armstead in, and we'll have to look further if we want Tretter. Again, then you look to Rowe and Butler (which I believe would be the next two).
Now, you have to ask yourself if a one year lease on Tretter is worth more than our 3rd safety and one of our better backup D-linemen when no help is forthcoming from this year's draft. That's a tough one.
Now, we get to the one area where I vehemently disagree with you. The LAST thing I would do is restructure Howard or Jones. That is extremely bad business to restructure a player who you don't expect to keep for more than another year or two. That causes some major cap pain when they leave. Players this old and close to the end (with our team anyway) require you to pay as you go... otherwise you get a balloon payment in 2024
Disagree with Howard and Jones, would like to keep the duo together and both should have 3/4 years left. The years of mortgaging the future are gone. The cap is expanding every year by 20-30 million. Nfl once again grew 9% more at this rate we will be looking at salary caps of 350+ million by 2025. Extending Gesicki is also an option. Plenty of moves to be made i don’t believe cap is a problem.