With respect to:

> My guess is that this is a big-retail liquidation of devices Apple is ready to move on from, and not a new long-term price point. We'll see!

I think this may have staying power. It provides a nice way of selling to a lower tier segment without impacting their higher tier offerings. It provides an on-route to the Apple computing ecosystem for those on slightly lower incomes who would otherwise have to go with the equivalent Windows laptop. Winning at that level gets people deeper into the Apple ecosystem earlier, and more likely in the future to stay in that ecosystem if their economic situation changes (classic example would be budget conscious students)