I'd say SHIELD is pretty much a PR effort to incite others to do exactly that - it creates buzz around the virtues of nVidia's mobile tech for gaming, and so could make licensing nVidia GPU IP an attractive selling point. I don't think nVidia expects SHIELD to be a high-volume seller on its own, it's pretty niche form factor-wise.

This is also why you have a bunch of graphically intense games on the Play store which are Tegra-exclusives, from developers who cut a deal with nVidia. For example Arma Tactics.