For the record, here is what happened to players the Patriots let go after the start of 2016 training camp up until the initial practice squad was formed. (I know some of these are veterans, but I was working chronologically and was too lazy to look up who did or did not have practice squad eligibility - so they are all here.)
While other teams may indeed sign Patriot castoffs, most of the castoffs don't go on to do much of anything elsewhere.
OL Kyler Kerbyson
Signed with Tampa Bay; part of final roster cuts; re-signed to TB practice squad in November; not with any team now.
DB Brock Vereen
Spent two days on KC's practice squad.
TE Bear Pascoe
No transactions since being released by Patriots
S Cedric Thompson
Signed by Minn to PS in October; released a month later.
CB V'Angelo Bentley
No transactions since being released by Patriots
CB E.J. Biggers
No transactions since being released by Patriots
RB Donald Brown
No transactions since being released by Patriots
DE Frank Kearse
No transactions since being released by Patriots
WR Nate Washingon
No transactions since being released by Patriots
DT Terrance Knighton
No transactions since being released by Patriots (retired)
OL Bryan Stork
Retired
LB Ramon Humber
Signed by Bills; played all 16 games, on special teams
OT Keavon Milton
Split 2016 between Dallas and Pittsburgh's practice squads
TE Steven Scheu
Signed by Denver to their PS mid-October
G Chris Barker
Spent 2016 on Pats PS; now with Cleveland
WR Aaron Dobson
Spent two weeks with Detroit, but did not play
RB Tyler Gaffney
On/off Pats PS; 2016 forum version of D.J. Foster is now with Jags
DE Geneo Grissom
Re-signed to Pats PS; appeared in 11 games for Pats
LB Rufus Johnson
Short time on Pats PS; in '17 has been w/Wash and Oakland
DT Markus Kuhn
No transactions since being released by Patriots
WR Keshawn Marin
Appeared in one game with SF in 2016
CB Darryl Roberts
Waiver claim by Jets; played in 12 games with 2 starts
S Vinnie Sunseri
Split 2016 between NE and SF practice squads; played in 2 games for SF
DT Joe Vellano
Spent 2016 on Atlanta's practice squad
WR DeAndre Carter
Out of NFL in 2016; now with SF
OT Jon Halapio
Spent most of 2016 on NYG practice squad
WR Chris Harper
Bounced between PS & active roster for SF; 9 games, 2 starts, 13 receptions
FB Joey Iosefa
No transactions since being released by Patriots
LB Kevin Snyder
IR/injury settlement; signed in 2017 by Denver
DT Woodrow Hamilton
Was on Pats 53-man roster for majority of 2016; also on PS
LB Kamu Grugier-Hill
Waiver claim by Eagles; played in 12 games, primarily on ST
CB Cre'von LeBlanc
Waiver claim by Bears; played in 13 games with 9 starts
WR Devin Lucien
Spent all of 2016 on New England's PS
TE Bryce Williams
Spent 2016 on Rams PS; has since been with Seattle and Carolina.
Original 2016 Practice Squad:
OL Chris Barker
OL Chris DeBord
DL Geneo Grissom
DL Woodrow Hamilton
LB Rufus Johnson
WR Devin Lucien
RB Bishop Sankey
WR Devin Street
DB Mike Hilton
S Vinnie Sunseri
Cuts That Played Elsewhere in 2016:
LB Ramon Humber (16 games with Bills on special teams)
CB Cre'Von LeBlanc (13 games, 9 starts for Bears)
CB Darryl Roberts (12 games for Jets, with two starts)
LB Kamu Grugier-Hill (12 games with Eagles, mostly ST)
WR Chris Harper (9 games with SF, 2 starts, 13 receptions)
S Vinnie Sunseri (2 games with SF)
WR Keshawn Martin (1 game with SF)
So here is my question: who from that final group should the Patriots have kept? Even with the benefit of hindsight, that also means that you have to keep some corresponding player off the 2016 roster.
Maybe Humber for Mingo, but at that time Mingo had a lot more immediate upside for the 2016 season. At the time it made sense to keep Mingo.
Perhaps LeBlanc for another corner, but which one? Cyrus Jones was a rookie 2nd round pick, and Jonathan Jones earned a roster spot with his special team play. Maybe LeBlanc over Justin Coleman, but that's mostly based on hindsight.
I think there may be a whole lot of unnecessary angst over the potential loss of players who will be part of the final roster cuts prior to week one in four weeks.