I'd say no to trading Trey Flowers.
The Pats still lack proven edge defenders against the run, which was a big part of last season's defensive failures. Flowers is one of only two or three proven edge-defenders on the current roster and could still be a critical piece of the 2018 defense in that area. And, with the additions of Clayborn and Shelton (plus the return of Valentine and HT), Flowers should have many more opportunities to "get home" on his pass rush in 2018.
If he hits double digits in sacks in 2018, he could easily command a contract that would provide the Pats with a 2020 3rd-round comp pick. The difference in picks received seems worth keeping Flowers for another season, IMHO.
My scenario:
The Pats traded the #23 + #95 (3rd) to the Browns for #33, #64 & #150 (5th round).
The Pats subsequently traded the #33 to the Niners for #59, #70 (3rd) & #128 (4th).
With the #31, #43, #59 & #63, the Pats have selected OT, QB, ILB and Edge-rusher.
On the clock now at #64, among the top offensive prospects on your board are Hayden Hurst (best TE remaining) and Dante Pettis (top college punt returner for four seasons). You still have the #70 (3rd), #128 (4th), #150 (5th), plus two 6ths & a 7th, but you have knowledge that neither Hurst nor Pettis will still be on the board at #70 (only six spots later).
Which do you choose?