Not sure about the Agency model, but the Kindle Apps and the fact that Amazon is fighting hard to maintain their position as the Coca Cola of eReaders is working well. The Kindle still has cachet. In fact, I'd say it has as much as the iPad in its market (with the understanding that the iPad and Kindle markets do overlap a little).
At this point I'd say as the Kindle goes, so goes the eReader market.
They really need to get the dang things in brick and mortar stores, though, and not just non-functioning models running a demo loop.