Maybe you can clarify what point you're trying to make. A Kindle's main function is to read books, not sell them. Likewise, a tablet's main function is to run software/apps.

edit: The argument that apps are more durable (in the economic sense) is questionable in and of itself; but even accepting the premise, that doesn't necessarily affect customer LTV, since durability is built into the price- the way a refrigerator costs more than a cooler and bag of ice.

We are on the same page- it does ultimately come down to LTV, and my intention was to show examples where it could work (other obvious ones are mobile phones and gaming consoles). I don't honestly have a figure on LTV of app buyers and if there was one I'd love to see it.