He doesn't have a return game so it will hurt him from ever making the top. Guys like Nishikori/Dimitrov have great all around games to be the next generation of greats. Milos serve is what keeps him alive and if its not there hes toast.
The point difference between 8th and 9th is big. But Del Potro will be losing all his basically. So its going to be a good fight for that 8th and final spot in London