LOL, this will no doubt help you elevate murray's status via an artificial and superfluous ranking system. sad.
He has 7 titles (almost 7000 points) to defend next year, so when it comes to defending all of that, how will he do it? He won't. So, how fast or hard will he fall? If he doesn't defend any of the titles, that's almost 3000 points lost, and that's if he reaches the final in all of them. Maybe he'll lose earlier in some of the tournaments? That means more points lost. Will he fall down the rankings? To no.3? No.4? Let's say he has the no.1 ranking then, will he just fall to no.2?
I think he'll defend a bit of the points (2500 let's say), but he'll fall down to no.3 in the rankings.