They're not talking about ending it's life prematurely. It won't have a successor (according to the article they cite), which given the likelihood it's replacement will be an EV was almost assured anyway. It doesn't mean they won't have a 4 door below the Phantom, it just may not be called the Ghost, in the same was the Wraith replacement was called the Spectre, and it may not be a simple saloon. Kacher suggests it's to avoid conflicting with a future B7, which is interesting as it could imply the B7 will be more than a 7 series trim level.