With 20 second confirms, a simple smartphone wallet app could solve those problems easily. At self check-out counters there could be a pay with (e.g., XenCoin) option and it sends the transaction as soon as you confirm that you are finished scanning all your items. By the time you bag the items the person on staff who monitors all self checkouts (those are still required, right?) could easily confirm any payments before the customer could theoretically confirm and dash out before the employee could verify. (And besides, if someone does this then you know they must be trying to get away with not paying because otherwise they could wait the maximum of 5 or 6 seconds at the most until they get a confirmation.
tl;dr 20 seconds is an optimal block rate because it maximizes convenience for the negatives that come along with having a fast confirming coin. Like anything else, it's give and take.
Almost perfect but first we need goods and services which will be offered for cryptocurrency. We need many merchants who understand the odds of cryptocurrencies.
Today nobody likes paper money such as USD but state authorities have power to force people to use them. Uncle Sam can point gun at you in case you dont want to accept that shitty banknote. Merchant cannot do this but they dont have to do it if customers wouldnot be at least against using coins.
I think merchants and shops that accepts cryptocoins are maybe more important than customers. I would definitely start from merchants.
Customers may ask for cryptocurrencies but if merchant is lazy or unwilling to make the change then nothing happens. However if merchant start to offer services and goods for Xencoin then people would come and gradually change their habbits.
Unfortunately very problematic is exchanging fiat money for cryptocoins. And also security. Because you must change your habbits how to handle with cryptomoney. However once a man finds the way and start using coins I think majority of people would not go back to fiat money.
Icobank project seems to be very promising unfortunately it is same promising as mysterious - one can only guess what it bring to us.
But even if it starts only to exchange fiat money for BTC and LTC and proved to be serious and not fraudulent they can become very well known. Now we have MTGox (constantly with problems), excellent BitStamp, BTC-e and than several minor projects. If Icobank has enough money from investors they can make huge changes in cryptoenviroment.