Wel...as I have said...there is no way we can know that....we just have to wait and see. If the heir dies...even after defeating Dagon, the gates of oblivion cant be closed, end of Tamriel...the daedra will just keepon coming....so i dont believe it will be like that...I might be wrong though...but if the heir dies...the point of the game wil be lost...tamriel weill be destroyed by an never ending tide of daedras.