Question is, how is S-500 developed for? Is the engagement in near space or is it on the warhead coming down to its target? Why I ask is because Global Prompt Strike that US is building will be allowed for US to hit any target around the world in minutes, with a conventional warhead/system. Now, in that case, Russia's both mobile and hardened missile bases will be prime targets for this thing, and Russian Air defense systems will need to be able to protect the bases from this device.
In the opinion article, it states that if thousand or more of the US system is capable of taking out 70% of Russia's missiles and then the ABM systems will deal with the rest, then that means that Russia would be incapable of using its ICBM's in retaliation, giving the US a false sense of security to attack Russia.
So things like S-500 and Morphi is what really becomes important. Are these systems capable of dealing with such a target? If so, then that means Global Prompt Strike system will become less viable option for US.