[account42]

You could try to upload them to modding sites (preferrably not onces with a longin requirement for downloading) if you don't want to host them yourself. That can be either general modding archives or game-specific community sites - the latter are smaller but more likely to be interested in older mods. Make sure that whatever host you use can be crawled by the internet archive.

Interest is probably going to be low but not zero - I often play games long after they have been released and sometimes intentionally using older versions that are no longer supported by current mods.

[Pannoniae]

You are entirely right - although I'd have to be careful with uploading it and where because on Steam Workshop, there's assholes who threaten to DMCA you without basis and there are similar problems on other sites too. But I'll look around :)