Wel, As far as the weaverBelt merchant, While initially it was so you can buy tabs for your inventory, due to game mechanics it would add items to the inventory even if i locked them. leaving players unable to retrieve the items that got shoved in there.
So, I put that on the back burner. but ill probably come back to it for Stash tabs.
As Far as anywhere at anytime, No what the plan is, but definitely a interesting Idea.
What id really like to do is make a mod that a player can be a merchant. Much like FFXI bazaar system. the player would be a walking Money taker event. with a custom UI if the player is clicked on, but of course ive not researched
the limitations that would be.

just an idea i thought would be cool if people still played together.