It would be nice to have a patent free alternative, but where is the money going to come from to get Codec2 developed to the point where it is a viable alternative to AMBE? As I said in another group where this topic has come up, it's hard to get investors excited about something that does a fraction of what existing commercial products do; besides, AMBE is under constant development itself and the version used in newer digital voice modes is backward compatible with what is used for D-Star.
As for the "single source" part of your argument, you're correct insofar as a turnkey solution is concerned for end user hardware; the repeater side has been available as hardware and software for non-Icom repeaters for several years and AMBE doesn't affect that side all that much, as those don't decode the voice data.