@Matthew Light
You touch many interesting points in your thread. Regarding the specific theme in the thread, I would use this hardware combo:
Trezor
Android phone with Mycelium
An OTG (On the go) cable between the Trezor and the phone
(Personally, I think Trezor should make a special edition with the OTG cable part integrated (not sure what it does, but I don't think it's just USB. Whatever...) And with the display upside down (or selectable). So you can just plug the trezor right into the bottom of your phone without cables. And sign all the transactions inside the Trezor hardware.)
However, as you say, this is a broader issue. I think it will be important to separate your coins in two stacks: Big bucks & Small bucks. (Maybe a level inbetween as well. But mid-level should probably be transaction rules from Big to Small.)
Small bucks: All you have to do in the shop, is hold your phone (or Fitbit or Apple Watch?) near the NFC-enabled cashier machine, read the amount on the device screen and click OK or Cancel. This is coins you can afford to lose. Like cash.
Big bucks: Nobody will try to rob you because the security is too good. And the robbers know the security system inside out before they consider it. If you want to spend this money, you have to prove to a second party that you are alive, and want to move the money. Then, four months (or some other period) later, you have to repeat that procedure before the funds are actually moved.
At the same time, you can have a customized amounts transfered from Big to Small at a time rate. Or have withdrawal limits with time restrictions.
I have not even started to talk about what this "Second Party" could look like.
I'll start a thread about this topic soon. Cheers!
PS. I hope I don't come across as arrogant or Mr. Know it all. But I am convinced that many people in the bitcoin community undervalue the security risk of holding lots of coins on a paper wallet. !00% risk free from hackers, but low hanging fruit for bad ass organized & informed criminals.