openSUSE have recently announced that their version number is going from 42 to 15 and that this is related to "SUSE have decided that their next version of SLE will be 15, not 13."*

I can't find an explanation anywhere for why SUSE have decided that the next version of SLE is going to be 15. Is there any one here who knows and is allowed to tell?

* https://lists.opensuse.org/opensuse-.../msg00014.html