It's kinda like when Miami came together, the chances for them to lose were greatest in the first season because they had to gut their entire team to get those 3 guys. They were playing bums at the other positions. Then the next year they got Battier, Ray after that, some other decent roleplayers etc.
GS is going to have to gut their team to sign Durant. Barnes, Bogut, Ezeli, Speights, Barbosa all gone. Yeah some of those guys aren't big pieces but replacing them with league minimums won't be easy.
As the years go on and they add the Battier/Ray/David West/etc of the world then it'll be tougher to beat them. Unless other super teams form or whatever.