Curry was 28, Green and Thompson were 26 and none suffered career altering injuries. Even without Durant, there weren't going anywhere. The question would have been, how many times would Cavaliers, Thunder and Spurs, have emasculated them?
I don't blame them for recruiting Durant, but at the same time, short of James signing with Rockets and them beating them, we'll never know if they could have been real champions (given Cavaliers' injuries, they didn't face a single contender in '15) and if so, how many times? That was what they forfeited by signing him.