From what I have read I believe the only way the Cs can sign Hayward (or any other max FA) is to trade AB or Smart and not retain KO and Zeller. I personally believe the following plan is the best way to compete now while building for the post lebron future.
1. Draft Fultz, in 2nd round draft 3 players who agree to compete in camp for the 2 new half nba / half g-league contracts
2. Trade AB+ Mickey + future lottery protected 1st for Carmel Anthony
3. Resign KO, Sign Zizic, Yabu, and Nader
4. Offer Amir, Gerald and JJ 1+1 team option deals
2017/18 Roster
IT, Fultz, Rozier, Jackson
Smart, Green
Crowder, Brown
Melo, KO, JJ, Yabu
Horford, Zizic, Amir
Rotation
PG IT 32min, Fultz 16min
SG Smart 30min, Fultz 12min, Brown 6min
SF Crowder 32min, Brown 16min
PF Melo 32min, KO 16min
C Horford 32min, Zizic 16min
This isn't perfect and Rozier needs to be figured out. He has earned minutes but they are not available. He may need to be traded and vet guard brought in on a 1 year deal.
Long term this rotation gives solid minutes to Fultz, Brown, Zizic and Smart. These 4 along with the 18 Nets pick will form the core of the Cs future. This future foundation has excellent position size and athletic ability at each position.