If this happens, the RPi-way of booting could end up enshrined as the way to boot ARM devices in the same way the PC BIOS did until EFI came along.
But maybe not, Microsoft will probably support EFI on ARM all the way. They do, don't they?
That's backwards because the raspberry pi SoC is backwards. The reason there is a "RPi-way of booting" is that the RPi is not an "ARM computer", it is a video core "computer" (technically the video core is just a graphics chip) running a proprietary OS called threadX that just happens to have ARM cores.
Yea. First Windows 8 RT ARM devices used UEFI + Secure Boot. I don't see why they would change the model.
AFAIK Windows ARM devices are currently all EFI based.