I really hope Linux can get a modern FS into common usage (as in default FS for most distros). After more than a decade ZFS and BTRFS didn't go anywhere. Something that's just there as a default, is stable, performs decently (at least on ext4 level) and brings modern features like snapshots. Bcachefs seems to have a decent shot.

What I'd like to see even more though would be a switch from the existing posix based filesystem APIs to a transaction based system. It is way too complicated to do filesystem operations that are not prone to data corruption should there be any issues.