In some comic arcs, Mystique has met her demise. However, comic universes can be complex and her fate can vary depending on different storylines and reboots.
It depends on which specific comic book arc you're referring to. In some, she meets her demise, while in others, she survives and continues to play a role.
Well, Mystique's age isn't precisely set. It changes based on comic book reboots and alternate timelines. Generally, though, she's been around for a long time, having been involved in many significant events throughout comic history.
There could be. Fanfiction writers are known for their creativity and coming up with unique crossovers. Given that both Harry Potter and Mystique are well - known characters from different fictional worlds, it's entirely possible that someone has written a story about Harry Potter being Mystique's grandson in the world of fanfiction. You should check out major fanfiction platforms like Archive of Our Own or FanFiction.net to look for it.