How many more days are the H.264 patents relevant?

Ultimately it doesn't matter whether it's accurate or not, because there aren't any free software decoders out there that only implement a subset of H.264. x264, which comes with FFMPEG, implements as much of H.264 as possible.

This wikimedia article focuses on High Profile, which is the most widely used version of H.264. It's really the only profile you need to support to be compatible with almost everything.

The official H.264 patent list from Via-LA includes 16 pages worth of patents, numbering in the hundreds. They even added a few more patents to the list recently: https://forum.doom9.org/showthread.php?p=2005047#post2005047

There have been over a dozen revisions to H.264 with more features added over time. Most of these features are not used by people who use H.264, or are non-critical. But because they exist, x264 will support them, and because they're patented, distributions like Fedora can't use x264.

Someone would need to create a H.264 decoder/encoder that supports only High Profile and nothing later.

Note that OpenH264 does not qualify, as its High Profile support is actually incomplete, so there are some incompatibilities. It doesn't support High 10 for example: https://github.com/cisco/openh264/issues/3616

And it doesn't seem like they plan to add it, given the lack of interest after 2+ years. Another LWN user, farnz mentioned in a previous article that OpenH264 doesn't fully support the parts of High Profile it does support; it gets around it with partial support for Main/High: https://lwn.net/Articles/1015494/

So, OpenH264 would need more complete support for High Profile before it could be a good patent unencumbered option even in a few years when all the H.264 High Profile patents do expire.