I'm wondering to myself, how are the Falmer still alive? I mean, they could reproduce, but the offspring of the Falmer shouldn't be blind, surely? Also, how is the Dwemer Corprus victim still alive? And I hope I didn't just go full...

The 'shrooms that the Dwemer fed the Falmer for generations made blindness a trait of the Falmer just like Frost resistance is a Nord trait.

Yagrum Bagarn didn't disappear because he was in the Outer Realms at the time and he's still alive now because Corprus makes you live forever.