If you have an Xbox Game Pass Ultimate subscription, you can stream Forza Horizon 2 (the Xbox One version) to your PC via xCloud. It works. However, it is streaming. You will have input lag, compression artifacts, and you are locked to 30fps. It is a "port" in the sense that the video signal is ported over the internet.
For a PC port to happen today, Microsoft would have to: forza horizon 2 pc port
. It runs relatively smoothly on modern hardware, though it lacks the visual features, traffic density, and seamless open world of the Xbox One edition. Why an official port doesn't exist: If you have an Xbox Game Pass Ultimate
Technically, you can run RetroArch on a dev mode Xbox, but that's a rabbit hole of lag and crashes. though it lacks the visual features