You have a couple interesting items in there. I'm tired so I'm going to ramble. Just my two cents. This sort of crosses into my IRL job. 
The "prepaid" card loaded with BTC is a very feasible idea. It would take some custom code given how normal CC transactions have so many prebuilt tools. Perfectly do-able.
If you want to have success in brick-and-mortar though, I believe the real key is having an arbiter willing to provide insurance for the retailer against:
1. Volatility against fiat conversion rates
2. The risk of accepting BTC without a large number of confirmations. (Can't leave the customer standing at a counter)
Other Barriers:
1. PayPal has some big pushes to get further into retail. They aren't fans of BTC. They have leverage on retailers.
2. BTC complicates an already messy space because of it's undetermined legal situation. If you were a Fortune retailer, are you going into the space wondering how the feds will react?
3. Obviously Visa and MC don't like this
4. People are distracted trying to catch up with other new forms of payment. Mobile wallets, PayPal in stores, Square... blah blah blah
Interesting trend:
Amazon is trying to get same day delivery by distributing their inventory into regional DCs. Obviously, Walmart is trying to creep into the Amazon space. Ebay is trying to squeeze between those by partnering with retailers who already have brick-and-mortar networks and use them as inventory. They are simultaneously competing as an alternative form of payment.
Maybe I should sleep.
The "prepaid" card loaded with BTC is a very feasible idea. It would take some custom code given how normal CC transactions have so many prebuilt tools. Perfectly do-able.
If you want to have success in brick-and-mortar though, I believe the real key is having an arbiter willing to provide insurance for the retailer against:
1. Volatility against fiat conversion rates
2. The risk of accepting BTC without a large number of confirmations. (Can't leave the customer standing at a counter)
Other Barriers:
1. PayPal has some big pushes to get further into retail. They aren't fans of BTC. They have leverage on retailers.
2. BTC complicates an already messy space because of it's undetermined legal situation. If you were a Fortune retailer, are you going into the space wondering how the feds will react?
3. Obviously Visa and MC don't like this
4. People are distracted trying to catch up with other new forms of payment. Mobile wallets, PayPal in stores, Square... blah blah blah
Interesting trend:
Amazon is trying to get same day delivery by distributing their inventory into regional DCs. Obviously, Walmart is trying to creep into the Amazon space. Ebay is trying to squeeze between those by partnering with retailers who already have brick-and-mortar networks and use them as inventory. They are simultaneously competing as an alternative form of payment.
Maybe I should sleep.