I think he will win the French.
People want to think that the Q-tip will win RG at some point, but I think nothing is less sure... he already burnt many occasions ... but not 2014 anyway, nor 2015, and unlikely in 2016 and 2017...
Nadal, if fit hopefully, will likely keep his momentum in the slams tournaments, and possibly even win a grand slam :
pessimitic Option 1 : USO 2013, AO, FO & Wimbledon 2014 , or,
optimistic Option 2 : AO FO, Wimbledon & USO 2014, yearly grand slam
Nadal winning AO would definitely increase his momentum for the bigger success. I will actualize my predictions from there.
Wimbledon still remains a question, but if he is through 1st week he could win...
Djokovic may have some of the remaining, but not sure because Murray could be back in shape by middle 2014, for Wimby or USO...
And some other outsiders may pop up, like Del potro, Janowicz, Wawrinka, or even Federer...
Djokovic may win some 2 or 3 sets matches but on grand slams his shape has decreased, so I see it difficult for him, i think Hhe has no more gluten credit left in his body, same for the egg...
So for the Q-tip I predict a 2014 with 1 GS (cf optimistic option 1 above) or zero GS (cf pessimistic option 2 above)