Death Note-Episode 23

Has to be one of the best episodes! 10/10 from me! The catch was amazing. I'm dying to know what happens next. My guess is that Light gets the death note again somehow, without L knowing.
The Chief got shot. Oh...this is bad. I think he will die and that will prompt Light to give in.

I have a doubt and if my doubt is true then the story has a loophole:
See, if a shinigami uses his death note to prolong a human's life, he dies. The shinigami used his death note to kill Misa's stalker and in turn saved Misa's life. So, she did not die on the fated date. That's why that shinigami died and his lifespan was added to Misa's. Therefore Misa's life was prolonged to quite an extent.
Now, Rem told Light that if he tried to kill Misa then Rem would kill Light. And Light said that if she saved Misa's life, she would die too. But, Misa's fated day to die will be somewhere very far away. Because we know her life span was lengthened by the shinigami. So, by killing Light Rem will 'not' be changing Misa's fate. So, technically Rem shouldn't die. So, Light's hypothesis was wrong. Hope you got it.