I think he's likely to retain his #4 ranking until after the Australian Open. The biggest problem will be the Claycourt season, where he's basically only defending points. Having won almost 0 points after that, he'll have to play extremely well to just stay where he is as far as ranking points are concerned. Even by his standards, 2012 was a great Claycourt season for 26 year-old Nadal. Can 27 year-old Nadal dominate just as much (I think the FO is still as much a lock as it can reasonably be, as it's over 5 sets. The Masters 1000 tournaments will be more challenging) so he can stay in the top 4? It could be catastrophic if he has to play Wimbledon seeded 5 or below.