I can't imagine any other death that is close to the X-Men that is going to be put on the cover of issue 17 other than Hope and Chamber.
I seem to read somewhere it's the leader of MLF ....
From the preview, it states the one who is going to die is one of the X-Men own members, Velo is not an X-Man.
https://www.previewsworld.com/Catalog/MAR190933
2MAR190933
(W) Matthew Rosenberg (A) Carlos E. Gomez (CA) Whilce Portacio
• First...the X-Men lose one of their own.