As you mentioned price still seems to be the sticking point for all the pundits and somehow has become the de facto tipping point for it's success. I am on the fence myself about this and, of course, the internet is a blaze with predictions and guesstimations a like. However, I can't imagine the price is going to be impeditive - if they are truly aiming at rolling out a new device every year and a 24 month upgrade cycle for it's users.
A reasonably priced packaging of the Shield with the latest video card that would entice and enable the user to experience the shield to its fullest performance capabilities is the most likely marketing scenario.
chi - Others have mentioned this as well, in several forms, and one we'll likely see. It has a four-dimensional effect - it help sells sheild, it increase production of T4, it accelerates the upgrade cycle of video cards, and deters/takes market share from AMD. I am sure this is one of many promotions we'll see.