We could extend the qualifying offer to him. And let him become a free agent when the cap is even higher. That would delay the decision another year, which I am fine with.
What teams/team have a need/desire for an undersized, unathletic, inefficient, center? Is anyone else going to be willing to offer a 12-15 million dollar contract? What teams?
Going down the list of cap space from most to least.
Lakers? No - Randle and Sully is a bad fit
Sixers? No - Already have Noel, Embiid, and Okafor
Hornets? Maybe - If they don't resign Big Al and Batum
Grizzles? No - They want to spread the floor with a stretch four
Blazers? Maybe - They would probably resign Leonard and Markless first, and need money for McCullom in the future.
Wizards? No - They want to go uptempo and already have Gortat at the 5
Bucks? No - They already have Henson, GiAnt, Parker, and Monroe
Hawks? Maybe - if Horford leaves
Pacers? No - They already have Turner and they want to play George at the 4
Jazz? No - They already have Favors and Gobert
Nets? Maybe - They need and will need to overpay for a point guard first, and then they probably would not have enough money
Pistons? No - They need a small ball four
Suns? Maybe - They may not have the cap space if they resign Teletovic. They already have Chandler and Len, and they want to spread the court for Bledsoe and Knight.
Mavs? Maybe - They need to resign Zaza and they will probably go after big fish, not Sullinger.
Pelicans? Maybe - If they resign Gordon and Anderson, they probably won't have space. They already have Davis and Asik under contract as bigs, and they need a versatile 3-4.
Nuggets? No - They already have Faried, Jokic, and Nurkic
Kings? No - If they resign Rondo, then they do not have space. They already have Koufus, Cousins, and WCS.
Magic? No - Is too similar to Vucevic that they want to spread the court without a true big at the 4.
Knicks? No - They need to invest in a point guard, and they already have Melo, Porzingis, Lopez, and O'Quinn
Bulls? No - They already have enough bigs and will probably resign Noah.
Thunder? No - If they lose Durant, they don't want another big
Wolves? Maybe - They already have Dieng, Garnett, Pekovic, and Towns.
Hornets, Blazers, Hawks, Nets, Suns, Mavs, Pelicans, and Wolves are all possibilities
I mean, there are better true centers ahead of him. Horford, Jefferson, Gasol, Noah, Mozgov, Zaza, Ezeli, Howard, Motiejunas, Hibbert, Whiteside, Leonard, and Biyombo are all competition for Sully. There is not a big market for big men anymore because of the new NBA, but especially not undersized, inefficient big men who can't shoot the three above 30%.
Who are we bidding against? I don't think anyone is going to offer Sully 12 million a year.