It's just an ARM with some specific Apple tweaks. You can get ARM machines now, from places like scaleway. I'm sure though that more "tweaked" ARM processors will start to arrive as other companies copy Apple. Also, I'd like to see what Intel does, now it seems that it's competitors are both beating them.
Intel, like Apple, prefer slow incremental changes, but I bet they could jump a couple of gens to pull it back.
Lucky for us Linux can run on both ARM and i686, but we would need our control panels to support ARM before we could think about making the move.