The barrier is the volatility. They still have to pay someone like coinbase to sell their coins immediately so as to minimize risk. It's too much of an unknown, and the floor has dropped out of Bitcoins on many occasions, and they could lose a ton of money in just moments. Retail is way too competitive to take on any risk.
None of the things you've suggested will minimize a retailer's risk, only a long track record of stability. Overstock sells their bitcoins immediately, they get transferred to Coinbase and sold as fast as the transactions allow. Their prices are linked to coinbase plus a healthy markup to pay for Coinbase's services and minimize risk. For such a large retailer, though, it also doubles as advertisement
This is why if Darkcoin can make a platform for retailers that they can easily implement into their payment systems that does the following, it will do more for Dark than people realize.
1. Buyers checkout with their purchase through Bestbuy.com or Overstock.com and instead of selecting paypal they choose "Safepay" or "Darksend" or whatever you want to call it.
2. On the backend, the retailer then would have software that performed an automated autosell feature that immediately converts the DRK to Fiat.
Doing this could be pretty difficulty and possibly time consuming if you had to first convert to BTC, then Fiat but the key is to remove the retailer's cost of implementation, keep any transaction costs low, and eliminate the retailer's exchange rate risk by having immediate fiat conversion. Maybe a Moolah.io type service is the best answer or maybe working some deal with paypal where from the retailer's perspective they are simply accepting paypal is a good solution. One thing that seems certain is that having a dependable, low cost exchange as a partner seems an essential component.
The coin at this point essentially needs to begin running like a corporation with employees that work to develop the relationships needed for retail integration. Those who have the greatest vested interest in making something like this happen would be the Darkcoin whales who are holding the most Dark. Those are the ones who will financially benefit the most by spending real money, time and effort to make this happen.
I know it's a bit utopian, but ultimately it would be much better if retailers held on to their DRK (or BTC). If not, you have a system in which people spend fiat or BTC to buy DRK probably hoping that it will increase in value, or in the worst case scenario, not fall. The you have retailers trying to attract customers who want to spend DRK, not necessarily because they believe in it but because they see an opportunity to make money. That would be ok, but when they trade directly for fiat the price goes down a little and the more success these retailers have, the more downward pressure there is on the price.
Of course for most retailers it would be impossible to hold all of their DRK (or even BTC) as they wouldn't be able to purchase new stock - depending on the goods being sold. Maybe some sort of system where sellers make a commitment to keeping a certain proportion of DRK could be implemented, say 0, 20, 40, 60, 80 and 100% of takings (or profit) for example. If consumers want to support DRK as much as possible they go to a site which keeps 100% of DRK from its sales, or maybe 80 or 60%. This sort of thing would no doubt be very difficult, if not impossible to police, but perhaps some type of trust system could be used.
