would this be possible to make into a plugin for players to use without having to install the mod http://mcpedl.com/villager-trading-mod/
That's my post and as I said in the "Edit" line: "This will be possible when it's officially implemented.". I'm not big MC:PE player nor fan, I don't follow updates. So @torudro, it's not a disagreeing!
Almost anything that can be done in-game in mcpe can be done by a server. It just has to send and receive the correct packets.