[lbearl]

I think the idea being presented is to physically own both devices, and simply swap the SIM card from device to device as needed.

[gohrt]

SIM cards/trays are not physically accessible and sturdy enough to make that practical as a daily activity.

A "family" plan across both phones is more likely solution.

[zokier]

I'd imagine that swapping (micro)SIM cards gets quite old quite fast. Heck, just rebooting phones all the time would be annoying imho.