Debian developers, glibc developers and many others have been working on this for the past few years. It's more or less solved for most free software applications.
Doesn't also count plenty of legacy servers out there that are on the MBA style of IT: Don't fix what's not broken and deny, delay, defend but for the IT department.
DOS, Win9x, and NT broadly speaking should be relatively fine though depending on how Y2K was fixed.
https://lwn.net/Articles/938149/