Well obviously Linux devs would love having ZFS in the kernel, Linus even half joked that he'd consider trying to relicense Linux to GPLv3 if it meant he could use ZFS and DTrace (this was back when Sun was considering GPLv3 as the license to use when going open source).
But the problem remains, CDDL and GPL are likely incompatible, and Linus has said that no CDDL licensed code will be merged, most likely per advice from lawyers.
So unless something drastically changes, ZFS is off the table, and thus work will continue on with alternatives, Stratis is one such alternative, bcachefs is another, and of course btrfs will not die just because Red Hat isn't supporting it anymore, as they barely did to begin with.
But the problem remains, CDDL and GPL are likely incompatible, and Linus has said that no CDDL licensed code will be merged, most likely per advice from lawyers.
So unless something drastically changes, ZFS is off the table, and thus work will continue on with alternatives, Stratis is one such alternative, bcachefs is another, and of course btrfs will not die just because Red Hat isn't supporting it anymore, as they barely did to begin with.