I don't see it replacing a phone. However, I might see it as being the SIM carrying heart of a local device universe. You could use it alone for Bluetooth calls and very limited (small screen restricted) functionality. When you want to carry your larger device, and have access to the larger screen, it could connect to the watch's radios. iPads could use it's radios. I'd also like to see a small Bluetooth keyboard of Blackberry quality that one could carry for heavy texting. I hate all of the soft keyboards.