Not by creating yet another online outlet, but by making the retail distribution channel obsolete:
The store is also expected to handle the single reason why Threadless is not available in major retailers: stores can’t simply keep up with a weekly turnover of new designs. Remember, they offer new designs each week– something that can be a headache for retailers.
Threadless is injecting serious value into the retail presence as well.
UPDATE: Chris Messina notes they are integrating OAuth too. These guys have a lot going on.