If Fai dies then that's it. I stop reading Tsubasa.
I don't care about Syaoran and Sakura anymore. I just read Tsubasa for Kurogane and Fai, their interactions, and the 'will they, won't they?' factor of their relationship. And for Fai's past, of course.
If Fai dies, or if Kuro dies at any point, Tsubasa is dead to me from there onwards,