Marketplace Idea

So my idea is, a marketplace!
For example:
1000 Elixir trade to 1000 gold, or something like that.
People can create their own offers, and people who like that offer, just accepts it.
There could be a timer, let's say I trade 1000 Elixir to 1000 gold, and that resources would come something in like 5mins, so it would look like the resources are travelling to you, not like just get them instantly. Also, it would be cool, if you could trade troops too, like 100 archers, to 5 dragons and so on :)

Resource trading has been ruled out.

If you can change gold to elixir 1 for 1, why even have two resources then at that point?