Thanks for you concern! The example you reference is a relatively new scheme; there are only two hits, both on your question today. Stack Overflow has nine hits, and I've checked a few and they all work.
However, the old scheme (e.g. https://forums.developer.apple.com/message/143196) has a lot more hits; over 450 across the network, 9 of them on Ask Different. A related search gives 224 hits (6 here) but some of them might be duplicate. And not all those links are broken, e.g. https://forums.developer.apple.com/message/11908 still works.
I do have some experience with mass-fixing broken links on Stack Exchange sites; I'll have a look what I can do. The main problem is that I can't fix them all at once without flooding the front page with old posts. There, I opted for a strategy of three posts per day. That might work here too.
Update: the first attempt at fixing them automatically isn't such a great success. Most of the times, the Wayback Machine didn't archive the link; when it does, e.g. this one, you can find the thread by looking for the 'canonical' link:
<link rel="canonical" href="/web/20161005194839/https://forums.developer.apple.com/thread/4276">
and use that link, https://forums.developer.apple.com/thread/4276, to get redirected to the current one: https://developer.apple.com/forums/thread/4276. My script fixed four of these cases on Ask Different (e.g. this one). For five more I was able to figure out from the context which message/thread it referred to, but there's no way to automate that (at least not for me). On Stack Overflow, it fixed 15 posts automatically. Next step is perhaps to collect all broken links, check which ones are often used and try to find the matching new link by hand.
