Smartwatch has been growing fast these years as it can do more and more stuffs besides just monitor your heart rate. A lot of smartwatches can work independently without connecting to your phone. They also can store sim card to make calls.
Smartwatches, smartphones and computers have their place because they have their own platform and processors. They will not be required processor at all in the future as 5G is coming. All the programs and apps processing will be done in a central computer also call cloud service. You only need a screen and 5G data transmit device. That means less power consumption for your smartwatch and makes no difference with smartphones and your computers.
Privacy is a big issue as we all use cloud service in the future. The company who has the cloud service will know all the activities we do online.