The main reason I'm making this thread now instead of later is to stop the rumor that Steam will immediately stop working on 7/8 on January 1st, 2024. We've seen the exact same wording with XP, but you still can (kinda) use the client all these years later. It won't immediately break, it will slowly break.
However, there's more interest in getting these newer versions working. You could pretty easily get 10+ month newer Steam builds basically fully working with some hex mods on XP/Vista, but by the time that was discovered, they were pretty ancient. However now we know where to look, so it's more likely we could mod Windows or the future clients to work relatively quickly. I doubt we'd get the same 10 months due to CEF being so important to the UI, but there's only one way to find out. More likely than not we would either need to make a custom GUI for Steam or kernel extend to fake 10 and make CEF work in the long run.
Just don't say it will immediately stop working. If you find someone thinking that way, please send this post to them. It is technically possible, however, it's not likely going by past events, or even viable to do.