For example, a band like Joy Division. Two masterpiece albums in the form of Unknown Pleasures and Closer, and the untimely death of Ian Curtis cut it all short. They were even heading into the direction that New Order eventually went in, and it would have been interesting to see what Ian Curtis would have done if they fully made the leap into electronic music while he was still alive.
Frightened Rabbit. Good body of work still but would have loved to see them keep going. Their music really hit close to home. Plus I only learned of them several months after Scott Hutchison’s suicide. What could’ve been.
+1 - I recently re-listened to all of his albums while creating karaoke versions of them all (here in case of interest: https://www.youtube.com/playlist?list=PLjPVqMYwkaP4zaPCEhTfkTyRspxoOyjfY ) and it made me sad to think how much of Scott’s reality was actually coming through in his lyrics.