Cool URIs Don't Change

They're ignoring the truncation problem. If I tell someone to look at the https://w3.org/something/6287297 URL, is that really correct, or did I botch a copy/paste of the https://w3.org/something/62872975 URL? I understand that https://w3.org/something/62872975.xml isn't optimal because XML might die. Is there a future-proof AND truncation-resistant approach, like always using https://w3.org/something/62872975.end regardless of the content type?

2016: https://news.ycombinator.com/item?id=11712449

2012: https://news.ycombinator.com/item?id=4154927

2011: https://news.ycombinator.com/item?id=2492566

2008 ("I just noticed that this classic piece of advice has never been directly posted to HN."): https://news.ycombinator.com/item?id=175199