I highly doubt Cousins is going anywhere, but my "all in" trade would be:
Wallace, Bradley, Zeller, and 5x 1st rounders
Brooklyn 2016, 2017, 2018, Cleveland (unprotected in 2019), Memphis (2017-2021 lesser protections)
AFAIK that would be the most picks ever traded for one player, and Bradley + Zeller are both useful players.
This would leave us with our own picks, plus a core of:
Smart, Young, Olynyk, Sullinger, Turner, Cousins @ $27M
We could sign 2 max free agents in the offseason, and likely gear up for another S&T the next summer. Let's say Butler & Green, and we draft Cauley-Stein as a high value defensive role player:
Smart / (vet min / exception?)
J Butler / Young
D Green / Turner
Sullinger / Olynyk
Cousins / Cauley-Stein
That team would be scary defensively with up to 5 All-Defensive caliber players (Smart, Butler, Green, Cousins, Cauley-Stein), and multiple scorers (Cousins, Sullinger, Butler, Olynyk and hopefully Young).
We would *still* own all of our own picks, plus anything we get for Bass or Prince or Thornton.