[adorno]

Maybe this device would be the phone? Just connect it to the “dumb” monitor-keyboard

It won't be the smartphone as it exists currently, but, it will be a powerful PC the size of a smartphone. The "phone" part of it will have to be detached, and probably be a separate wearable, like the "smartwatches" of today are and which depend on people carrying a smartphone to "operate" as the smarts for the smartwatch.

I can see the "future" PC itself being a wearable device, and which can actually be hidden and not even having to be touched or taken out of wherever it's kept on the body or purse or pocket or wallet. Your "PC" will go with you everywhere, and the peripherals will either be carried as separate wearables or can be remotely connected to (like storage device) or can be any device within proximity of the PC which can be connected to, like a TV set or monitor.

Reality is that, with cloud services, the PC of the future won't even need to contain the smarts that PCs have traditionally had. The "PC everywhere" will be like a "dumb" terminal, but much more powerful, with the power being supplied by remote computers and cloud services.

[MrEdd]

There is no reason whatsoever for the phone part to be detached.

There will also be smaller phones, but people are carrying around six and seven inch phones right now. 14nm dies will shrink a full windows machine to that form factor.