I have heard arguments that Oracle would now be the License Steward and could change it to be whatever they liked (GPL 2.0, MIT, etc.) which would flow to the OpenZFS project.
See section 4: https://opensource.org/licenses/CDDL-1.0
See section 4: https://opensource.org/licenses/CDDL-1.0
Another issue is that what is specifically a problem with GPLv2 is that CDDL-1.0 provides patent litigation indemnity, losing which would be a big problem.
I mean, with an open source license, who could get sued, anyway? The current steward of the main repo?
CDDL has provisions that mean that Oracle can't sue you for (hypothetical) patent infringement in ZFS code because Sun gave automatic license to those patents when it released code under CDDL