I’m not sure at this point if that means basing it on a different CentOS based fork, looking at alternative distributions as an option (debian, ubuntu, etc), as a lot of that has yet to be determined and needs to be well thought out.
Or maybe the CentOS guys will realize after all the community backlash what a bad idea it was and this will all go away. Or not.
I’m sure the hope from your end is that IBM/Red Hat/CentOS reverses course or that the project forks and returns the Community Enterprise OS to the community it’s named after, obviously that’d be the lowest effort path forward.
If that doesn’t play out though, I’d definitely put my vote towards a Debian base. Ubuntu LTS would be OK as well, but the advantage I see to Ubuntu is mostly in the PPAs that are less relevant to a purpose-specific distro, so without that as a major factor I like sticking close to the root of the tree. Most of my headaches with FreePBX Distro have been related to quirks of the RPM system so I’d be glad to have the next one be APT based one way or another.