This is interesting if somewhat belated. Being able to run Windows apps is not as much a killer feature today as it was, say, 5 years ago. Microsoft now has its Office apps on iOS and Android, and they’re usable enough on those platforms for many people to not hanker for full fat Windows experience.
One potential impact this may have is on Apple’s devices. One of the factors that boosted Mac sales was Apple’s support for Windows through Bootcamp (as well as virtual machines like Parallels and VMWare) following the Intel transition in 2006. It allowed people who wanted to try Macs but were still tied to the Wintel ecosystem to make their purchasing decision much more easily. If Windows is emulated acceptably on ARM, it may enable one or both of two things: one, if/when Apple transitions Macs to ARM they will retain the abovedescribed Windows support (Apple would still need to oversee transition of existing Mac apps to ARM, but that’s another story); two, Windows being potentially available in some form on iOS devices (I don’t have any technical knowledge to even guess, but wouldn’t it be neat if Microsoft could package fairly full-featured Windows emulation in an app? They could earn some good revenue with a one-off payment or more likely annual subscription). Neither is crucial to Apple’s future plans, but they are going to be helpful for certain sections of the userbase.