>"emulating" the (fairly small) subset of the traditional Win32 and DirectX APIs required for typical games might even make sense on Windows itself, should Microsoft one day decide to deprecate
I recently tried to run some WinXP-era games on modern hardware, and had absolutely no luck on Windows 10.
However some of the games ran fine on Wine (and 64-bit Linux).
The only downside I see to emulation is latency, but for many games this doesn't matter, and it's worthy to keep them runnable like this.
There shouldn't be significant latency issues, unless there is large amounts of (CPU) work that's required to make large data structures compatible(for a silly example, imagine that the texture formats are different and you need to convert between them). Or if you need to simulate a single function call in a tight loop with several calls.
But the overhead is usually not much more significant than what you get when you import a library to call OS functions on your behalf, versus calling them yourself.
I recently tried to run some WinXP-era games on modern hardware, and had absolutely no luck on Windows 10.
However some of the games ran fine on Wine (and 64-bit Linux).
The only downside I see to emulation is latency, but for many games this doesn't matter, and it's worthy to keep them runnable like this.