None of these qualify as "mainstream" compared to RedHat/CentOS/Fedora and Debian/Ubuntu. Even SUSE, which used to be in the big league, is a shadow of its former glory.

If you look at what runs on production servers, it's virtually always RHEL/CentOS, or Debian/Ubuntu. Everybody else isn't even above 5%, and most of those you've listed are in fractional digits.

For another data point, if you look at websites, Debian+Ubuntu is already >50%. At this point, I think it's well on its way to becoming the Linux distro, with everything else being relegated to the hacker/boutique niche. And I think that this announcement, and what IBM is likely to do with RHEL afterwards, will accelerate that trend substantially.

Shame. As far as I can tell OpenSUSE & Fedora are on the same level. I often struggle deciding which one to install on new servers because I love them both so much.