I wish you took your time and make changes to Retrozilla to support modern web,but at this point it's mostly the creator's doing.
As for Windows 7 and 8.1 users,if 115esr ends support,will you fork 115esr and update it?
Also another question,Do you plan to fork Firefox 12 (last release of firefox for 2000 and XP RTM-SP1 users) and upgrade the NSS library to the one compatible with the modern web?