Reason? From the situation you describe, it is just a small step to "store everything in the cloud; authenticate with your phone" (most locations with a keyboard, mouse, and monitor that people who can afford a fast phone will visit will have fast internet connections, and will easily have the 10W power budget needed to beat your phone, performance-wise)
You would have to trust the hardware you use, but you have to, anyways, the moment you plug a modern keyboard or monitor into your phone.
Yes, you would be ensured that the software you use on your phone is compatible with the software you use on your 'desktop' because it is the same software, but you also run the risk that it is suboptimal for either (the fonts may be too big for power desktop use, or you might need a pen for manipulating some not-too-often-used controls), and in the 'use phone to authenticate' scenario, you run less risk of running your phone's battery dry.
Ultimately I think the final outcome, which may take many decades to get here, is a device embedded inside of people that give them access to everything they need and if they need another way to interact with the information they'll use some sort of dumb terminal (because if everything is embedded in you and can be accessed easily via some wireless protocol, why would you go through the hassle of a separate authentication step where all your data could be exposed).
Whether there is a market for this today or not I don't really know. I'd love to find out but this is the type of thing that would require quite a bit of start-up capital and an MVP might be difficult to do.
Um, what? Why would you carry around all that stuff? I clearly described scenarios in which places would already have that setup for you. You just dock and go. Just like today you don't carry a router around with you or anything else.
> A desktop is going to have more power, a laptop is going to have a form factor that's much more convenient to carry around, and more battery.
"More power" doesn't mean anything without context. If you're just writing papers, code, even playing some types of games you likely have plenty of power for this already in your phone. If you want to play FarCry then obviously yes you're not going to do that from a phone.
A phone is more convenient to carry around than a laptop. If someone can supply you a laptop that your phone simply docks with you wouldn't need to carry it around which is precisely my point: the phone (or possibly another, smaller device) could be your personal computing platform and everything else around you simply visualizes the data contained within.