In my experience it may be worth archiving the 264's to multiple cheap storage devices if that is an option. Why? A time passes there are improvements to tools/libraries like ffmpeg and every {n} years I have found that re-encoding a file from its original source to 265 improves. Errors/flaws in the source file are handled better, less content is lost and the end result improves as ffmpeg and related tools evolve. This is only useful to know if you have an abundance of storage to keep your older files around and care about such things. I understand that many people do not.

[Edit] I forgot to add this methodology is also useful if the videos were downloaded from a platform like YT. Future versions of libraries can handle stripping out proprietary meta-data and other garbage from files that was intended for their JS players but useless for archival and local playing purposes.