Wow. This post is very well done, and perhaps really took a lot of effort to make.
The thing is, unless we have more than 1 bitcoin this may be an overkill. Especially for non techie people. It really is rare nowadays for a regular household to have an "air gapped computer". So if i've got a quarter of a bitcoin right now it would be impractical for me ( cost-security ratio) to do this. Please don't get me wrong. This is a wonderful Idea, and I could be kicking myself in 10 years when I have 0.25 Bitcoin and I did not took extra efforts to secure it and it will be $50,000 by that time. :)