Unfortunately the predictions as far back as 2005 that Nadal's body would limit his longevity are indeed proving correct.
well to say the truth, I didn't expect him to play that well in 2011 (he played great, only Djokovic was too good) and the beginning of 2012 then already he surprised me. Comparing to grinders of the past like Wilander or Hewitt, he already stayed quite better than expected.
And now he's off because of one problem which looks independent from all of his previous problems and seems to be a problem which will not hamper him in the long term.
Also mentally, he got back well from his losses to Djokovic this year (also thanks to Djokovic's poor performances and stupid errors this year on clay esp. against him).
Then well that's impossible to bury his hopes now imo.