The title is a little unfortunate, implying that Roger doesn't have the ability to win, rather than suggesting that he isn't in the form, but I agree with the prognosis - Roger likely will bow out in the semis.
To me, the Wimbledon win was his main goal and his motivation/energy/fighting instinct haven't been the same since. This is not to take away from Berdych, Murray and JMDP anything for beating Roger. But purely from Rogers side, he hasn't been able to sustain the intensity after the draining silver match against JMDP at the Olympics.
Perhaps he tried through sheer will power to hold on to the no.1 for as long as he could with the trip to shanghai but I don't see him really very perturbed with his form/losses. (notably with the serve)
He played a long season in chasing no.1. I think we won't see him back in form until next year..