I was just looking at who's playing this week and next week, and it is possible that JC could end the year in the top 15 (or at least 16-17)...other players will have a lot of points to defend.
ToJo has 240 - 15 from Moscow that he won't defend, and 220 from winning Stockholm
After Moscow points fall off, he'll only be 185 points from JC. As long as he doesn't get further than the Semis in Stockholm, JC will pass him.
Richard Gasquet has 170 points to defend in Moselle from reaching the final, he's still 320 points ahead of JC.
LaLo has 270 points, 250 from winning Vienna last year...so this pretty much guarantees that JC will stay ahead of him.
Hrbaty has 110 from QF in Kremlin, but he's playing in Moselle and Moscow the next two weeks. JC is currently 14 points ahead of him.