This! I believe this is the key: the rise of the smartphone has led to the death of the handheld computer. These are two flavors that do NOT taste great together: a general-purpose computing device, allowing the user to perform whatever tasks they wish, and a telecommunications device, designed specifically for both high availability and to work within the constraints of cellular service providers and national communications laws.

In order to be available at any moment, a smartphone has to be small enough to comfortably fit in a pocket, pretty enough to not embarrass the user in public situations, and constantly spend power waiting for incoming calls. Modern devices have sacrificed flexibility and user freedom in order to achieve these goals. And they've succeeded.

So really, the key to getting back to portable computing is to just completely ignore the entire cellphone industry. Get a phone for phone calls, and get something else entirely for portable computing. A tablet, a hacked-together Raspberry Pi device, a Pyra, really anything that avoids the insanity of the cellphone industry...

Anyway, that's my opinion.