2011 and 2012 Wimbledons. Nadal can't shake the clay dust off his shoes and can't conform to grass efficiently. By the time he can finally get suited to Wimbledon grass after a long and taxing clay season, he's toast by the 2nd round (Rosol 2012) or a deer in headlights (Djokovic 2011) or barely getting by some lesser ranked opposition (Haase/Petzschener 2010). Nadal has clearly been struggling with his grass game over the past 2 years and it was exposed. He's not a super scary force on hardcourts. So clay is his best bet. I believe he will continue to aim for RG until he is broken down. He should get at least 1 more RG title if his body holds together or if his desire is still there or if he can avoid a resurged Djokovic 2.0.