When about do you think firefox will no longer build for X?
Python 3 was ready in 2008 but 2 will be supported by RHEL until at least 2024 16 years later. I will be surprised if in 2030 I can't simply pick distro with X and fire up firefox. Its kind of silly to expect users who are disinterested in using foo to pitch in to make foo acceptable when said users really want bar because you tell them that bar is now the standard "get over it".
