Software depends on its hardware. If the hardware dies, or no one writes an emulator, that program will stop being used. But even if a particular incarnation

Software depends on its hardware. If the hardware dies, or no one writes an emulator, that program will stop being used. But even if a particular incarnation of an idea is no longer used, it will exist on modern hardware if it is still a useful thing to do (via a port, a rewrite, or even as a dedicated part of the hardware itself). That isn't to say it won't cost more to keep an older design afloat, but it happens all the time. Some forms of emulation are not even obvious to end users. For instance, there is an alarming amount of effort spent on Windows operating systems and the Intel architecture to enforce decades-old decisions so that programs expecting certain behaviors don't require code changes. You may not know it when you run something, but its very ability to execute can be the result of a hack upon a hack at both the software and hardware levels. It's not even that uncommon for a platform to say "if program A, apply hack X; if program B, apply hack Y; else hack nothing".