> Most JavaScript-based single-page applications from 2010 should still run flawlessly in modern browsers.

If they're purely client-side, sure, but there's a good chance that anything we could reasonably call a web application, also has a backend component on a server. How confident are we that the backend code from 1995 will still run?

1995 is when Microsoft Frontpage launched. PHP was a year old. I'd be surprised if anything written in those sorts of environments still functions without being run on a 1995 version of Windows/Linux on 1995 era hardware.

Software is a process, it always has been, it always will be.