No, once your data is in the cloud you'll want to access them from a trusted device, not from *any* device. End-to-end encryption is not safe if one of the end is not trusted and could be compromised. Thereby a small yet powerful enough device can make sense. There's the "dock" issue, of course - it it could be made wireless with most devices you can find around you, it could work (although there could be some security issues as well).
But it's not true people like to carry around many separate devices. Smartwatches are still mostly a product looking for a consumer, and some "tablets" ate into ultrabook and laptop sales. I'm very happy with my Surface because I have only one device to carry around - I would hate to carry both a tablet and a laptop with me.