It's not a matter of market, it's a matter of ability. If I remember right (been a while since I talked to an engineer about it), the issue is that Apple doesn't provide an API that can be underlaid with a virtualization engine easily. That means it's more a matter of emulation, which is a far harder lift.
Folks who are going to be running out of date, unsupported OS's and software need to make sure that those VM's are in isolation mode - no network access ideally, and definitely no internet access. Otherwise they're at high risk for compromise. For example, I have one, very old piece of software that I run in Windows XP (ok, it's a game). That VM doesn't even have host networking activated.