I was thinking about starting a dinasty too until i saw Iguodala's defensive stats, lol. With his current numbers he will be the DPY in just a few season

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Anyway, i don't think there is a realistic way to make what you are saying.
T-Mac in Houston as well as Amare in Phoenix are keepers. James in Cleveland is a locked.
As regards KG, i believe that if you come up with a good story it could be somehow realistic however not with Cleveland.
First, i say it could be semi-realistic if KG is traded because Minnesota are looking really bad right now. Kg wants a championship and the wolves are far away from that. Thats way Kg could ask to be traded.
Second, i say kg could not get to Cleveland by a realistic way because in order to get him you should involve Hughes and he just got to Cleveland in order to stay for the years to come.