It will never happen unless that currency covers all expects of the ingame items . This includes craft / rolling supplies, all items and services. But, that is another subject. My thread is NOT about a strict trading / bartering system, the feature is meant to be a great add for D3 communities . They don't need to barter for an item because a lot of them give items away for free. Know the amazon basin? Or Gaus in Europe? I don't know how you see it but if you mean trade like "i have this item let's see what i can get for it in terms of other items" then indeed a face to face transaction is the only possibility as it can never be implemented in a feature like this.
This is no bartering system but an easy and very accessable way for players to transfer items between their own characters or between friends. (the fix for muling issues would be worth it alone). Anyway you like it or not. If you find this a bartering system that should never be implemented in D3 than that's your opinion.
btw i have seen several threads where bartering systems were being discussed but i never saw one where someone sugested to tie a trade with an account name. Also not solving muling issues at the same time ;)
So what you're saying is that you want a mailing system of some type. I'm not sure I understand what you're talking about any more.