Fed must improve his game and hope to have a really strong HC season because he is at risk not qualifying for WTF this year. btw, the next tournament he'll be playing is Gstaad. It's a 250 clay tournament. Fed got a WC. He needs points desperately, plus he needs to play more in order to bring his game to a higher level.
He still looks likely to qualify to the WTF even with a less than strong HC season. He's 5th in the race before Wimby and will likely fall to 6th or 7th, not further down. Janowicz would have to win the title to catch him, and even the title wouldn't be enough for Verdasco or Kubot, so it's only a question of whether DelPo passes him or not, for which he'll need to reach the final. So most likely 6th after Wimby. He'll then need to not drop more than two places. For the WTF, he can afford to be passed by DelPo and Tsonga just so long as noone else slides past him as well.
Currently he's got 2515 points. 3500 points has always been enough to qualify. Last year the best non-qualifier had 2990 points. The year before 2965 points. In 2010 3240 points. 2009: 3010 points. You have to think Fed is going to get over that threshold if he avoids injury. He won't have to beat a top player, a few QFs in big and SFs in smaller tournaments will be enough. Anything more than that and top-8 will not be a worry.