Hi Serkan,
Do you think that after a point, system can ask for a SP upgrade any other component other than SAP_BASIS?
To be frank, I have no idea. I've been asking myself if there's gonna be a point where the applied notes are, let's say, "too far within a future upgrade package, be it SP or Stack" and other dependant portions of the system start to malfunction. But up until today this has not happened, I guess also because we are always only 3 or 4 package levels behind the maximum available package.
Cheers, Lukas