That's what VM's are for.
Upgrade your hardware, upgrade your OS, install and configure the VM, copy some files, and you're running the legacy OS and application again.
Yes. VM's have their place. No. They don't solve the underlying problem for all application cases. As applications get more and more advanced and the need for performance increases VM's are simply not a viable option.
Yeah sure, there are edge cases such as FEA which cannot be virtualized without dramatic losses in performance, but unlike the cherry picked examples, floating point operations are not the critical path for most applications.