Cashman has made four trades in six days, less than 48 hours to go. It is kind of crazy to do this much dealing for a team on pace to win 104 games, but some of it is continuing to set up for 2019 and beyond.
But if it was up to me, I would still try to do a lot actually, as always depending on price and return, but:
Trade Warren, he can probably bring something back and he is a FA and replaceable, start with Kahnle or Tarpley or Feyereisen or Espinal, Acevedo when healthy is an option here too.
Trade Gray to MIL or OAK or ATL if you can get a good return, I think you can. Bring up Sheffield and make him the 5th starter, not only does he have a seemingly rejuvenated Cessa (5 strong starts in a row, 3 in AAA, 2 in MLB) behind him but once they get to Sept 1, everyone on the 40 man can be up and German and Acevedo and Loaisiga will all ideally be back by then. Also getting a look at Sheffield for a few months will help both him and let NY get a better idea in what they have in him before they have to make offseason decisions in the winter of lots of money to spend if needed.
Bring in a DH type, Jose Martinez or Mark Reynolds or Matt Adams, someone like that who is available for not too much, Thairo Estrada and Chance Adams are two more 40 man guys I'd move if needed, both were top 100-150 guys just last winter but have been passed. Martinez would be ideal as he is still pre-arb, I'm sure there are other options too.
Trade Tyler Austin if he has value, if you are not bringing him up now in favor of Shane Robinson or in the above DH spot, just let him go. This might be more of an offseason move.
I don't know if there is a roster spot, but a cheap Billy Hamilton acquisition for late inning defense and/or pinch-running is tempting if there is. I'd suggest Austin for Hamilton, but they have that Votto guy clogging things.
Don't trade for Chris Archer.
Compete for a championship.
Sign Machado and a pitcher for the Gray spot in the offseason, maybe Patrick Corbin, maybe JA Happ, maybe someone else. Resign Britton if he stays healthy. Let Robertson go (sorry David). Keep Andujar as the bench 3B/1B/DH. Keep Frazier, let Gardner go (or maybe pick up his option and trade him, sorry Brett). By position in 2019:
Sanchez
Bird
Gleyber
Didi
Machado
Stanton/Frazier
Hicks
Judge
Andujar/Frazier/Stanton
Severino/Tanaka/??? (Corbin or Happ?)/Sabathia/Sheffield
Holder/Green/Britton/Betances/Chapman++
Compete for the next bunch of championships.