Magnum_Force
Newcomer
The problem of making it part of the Surface line is that you effectively price it out of the market, and it doesn't need to be so costly.
Also the Surface form factor isn't ideal for a handheld which doubles as a base unit, as it makes too many compromises to achieve its tablet form factor.
In my opinion the best way to make such a device would be to have a "base" unit with detachable screen. The base unit would be more akin to laptop in form factor, and the screen would simply attach to it. This would also allow Microsoft to simply sell the base unit as a non portable (without battery and screen) for people who didn't want that functionality and the extra expense that goes with it. It would also allow people to "upgrade" their base unit to a mobile later down the line.
Also the Surface form factor isn't ideal for a handheld which doubles as a base unit, as it makes too many compromises to achieve its tablet form factor.
In my opinion the best way to make such a device would be to have a "base" unit with detachable screen. The base unit would be more akin to laptop in form factor, and the screen would simply attach to it. This would also allow Microsoft to simply sell the base unit as a non portable (without battery and screen) for people who didn't want that functionality and the extra expense that goes with it. It would also allow people to "upgrade" their base unit to a mobile later down the line.