How many XRP do you need to get to the next level?
No retort. I imagine these things would end up in Ripple too. Either directly through the card companies or through 3rd parties. You'd get your airline points or credit card points or whatever (which are essentially another currency), and these could be paid by the company directly into your Ripple account which you could then trade for BTC or do whatever you wanted with them. I could pay for my pizza in airline points. Seriously. The merchant would get US dollars (if that's what they sold pizza in) and I could pay with my AA frequent flyer miles. Can your bank do that?
FF miles would be worth how much. Not $1 each for sure. Would there be a market for trading FF miles. I don't think any airline wants people to dump the miles for cheap. What if a few people bought cheap and had a lifetime of free miles when they normally would have paid 10x more for those flights in USD. See the problems here already?
There is way too much programing and networking and logistics between the companys involved. These players already have sweet deals with each other so why let a new player in the game. It just don't make no sense.
I think the issue of fairness is a huge deal breaker for most people as well. I doubt I would ever buy a ripple because of the distribution system alone. Bitcoin was not 100% fair but I think its a close as we will get and like some one on here just said its the money people have invested in bitcoin mining and the security that it provides that give it staying power.
The demand for ripple may come to a trickle...
There would be a market for FF miles. There most likely will be whether airlines participate or not. If there is a market in FF miles and I have them, then Ripple will find the best path for me to pay someone in the currency they would like to accept (I can accept or decline to take that path).
As to the programming, I'm pretty sure it's simply a matter of interfacing with Ripple using the API, although that certainly isn't my expertise, so I don't want to say I know for sure how difficult it would be.
I think the "fairness" thing has to do with people thinking there is only one way for a currency to be distributed and the fallacy that "mining" somehow made that fair. In both cases the original programmers got a big chunk of the original coins.