>That said, one of the interesting "advantages" that Samsung and Apple get here is that they are their own SoC vendors.

Both Apple and Samsung heavily use Qualcomm products. The Samsung S4 is powered by a Qualcomm Snapdragon 600. It should say something when Samsung isn't using it's own Exynos for it's premiere flagship device. The S4 also features a Qualcomm 4G LTE modem. And a Qualcomm power management chip. And audio codec.

The iPhone5 is almost as Qualcomm heavy itself, too.

I think Samsung and Apple would have equally as difficult of a time trying to release binaries (or source) as well, regardless of who is designing or assembling the SoC!