Hmmm... i don't think that a nexus prime (even a could-have-been) would have LG's UI. This could be that LG added their UI when their phone was rejected for the Nexus spot, though.
Actually, I thought they might have submitted this one for nexus device, then put their skin on after they got rejected... Apparently this phone is coming out one way the other.
That's a "Concept Phone," which is code for "Made up **** we think looks cool." They could have made the logos a little more out of proportion, I suppose.