To me DeRozan has got to stay otherwise you blow the whole thing up and we'll be terrible for the next 4-5 years, so I'll take his word that he's loyal to the Raptors. I'd offer him the max or maybe a lower amount because you're allowed to offer him 5 years versus 4 years.
There is absolutely no way KD signs in Toronto without both DeRozan and Lowry around, but if you sign Derozan things start getting interesting. They won't have salary cap space for KD, but 20+ other teams will. I'd start working the phone lines to trade Valancuinas and Ross for future picks and it's not like those guys aren't worth anything either. Of course if you know you won't be able to sign KD you keep Valancuinas and Ross roll with what is currently the second best team in the East.
Either way Derozan stays and the Raps continue to build to something.
Biyombo
KD
Carroll
Derozan
Lowry
One can dream
