I'm curious just what definition you're using for "crumbling foundation". Is it that old software doesn't break on it, in which case PHP/HHVM/Hack isn't a crumbling foundation either - Facebook is built on it, and Facebook is clearly still running.
Or is it that maintenance is difficult and programmers will run into all sorts of ugly corner cases and features that are just grafted onto each other? Because those apply to C and C++ and Win32 and Google and basically every other large software system as well. That's the point the grandparent is making - if you look at pretty much any successful, evolving software system under the hood, you'll see a byzantine mess of complexity, and it's a wonder that it ever works.
Or is it that maintenance is difficult and programmers will run into all sorts of ugly corner cases and features that are just grafted onto each other? Because those apply to C and C++ and Win32 and Google and basically every other large software system as well. That's the point the grandparent is making - if you look at pretty much any successful, evolving software system under the hood, you'll see a byzantine mess of complexity, and it's a wonder that it ever works.