Nope this is wrong. A simple thing called gravity will force them down. They will not have fuel to keep them up.correct but they, being SAS, will not by force "bring them down". There will be an overlap between the "old" and the "new" which was what I was getting at then yes i agreeI don't think that the satellites that are past their operational life will be "coming down". Rather they will stay up there as a backup once new satellites are launched, or will just become space junk once replacement satellites are up.
This makes more sense than them bringing them down to earth
all imo