What do you think about this "Bitcoin-backed money" idea?

[Ultrafinery]

Lightning Network is the pipeline with a first functional version for this year.Then you won't have to wait a few minutes if you are going to buy something with Bitcoin of bigger value.

You will, otoh, have to pre-fund all your purchases, as you would by buying a gift card. In other words, if you want to use Lightning to buy your Starbucks coffee, you will first have to "create a payment channel" and fund it with enough bitcoin to cover all your future purchases.
Just like buying a gift card.

[Wendigo]

This idea simply won't work because Bitcoin is a decentralized digital currency that can't function normally as a centralized paper-based physical money. We would need some kind of authority to issue these paper Bitcoin certificates otherwise people would go on a rampage scamming each other with empty wallets. How are we going to verify that the displayed amount of Bitcoin is actually not spent already? Plus the public Bitcoin key that is visible might not match the fake private keys that are enclosed inside. People would need to open and check the private keys upon every transaction and this will be definitely much slower than just transacting the coins digitally and be done with it.

[Harpua]

This idea simply won't work because Bitcoin is a decentralized digital currency that can't function normally as a centralized paper-based physical money. We would need some kind of authority to issue these paper Bitcoin certificates otherwise people would go on a rampage scamming each other with empty wallets. How are we going to verify that the displayed amount of Bitcoin is actually not spent already? Plus the public Bitcoin key that is visible might not match the fake private keys that are enclosed inside. People would need to open and check the private keys upon every transaction and this will be definitely much slower than just transacting the coins digitally and be done with it.

I hate to be that guy, but you know in this case that it would be the government being that kind of authority.  There would need to be some sort global system that logs all the "physical currency" private keys and put them into a data base that allows a quick scan at the register to check and see if the note is "viable"...

This is way too much, I think, and there will have to be another way for delivering small payments for everyday transactions.