"western" FPS...I think he may mean a FPS with the style of a western (North American or European) developer.
And yes, Retro does seem poised be that developer. They've done two Metroid games, but members of the team have a FPS history. I actually think we'll see a Retro FPS that borrows level design touches from the Metroid Prime series and meshes them with more standard FPS guns and a huge focus on deathmatches. Metroid Prime fans would enjoy the huge world exploration, and Metroid Prime dissers (who wanted a normal FPS controls scheme) get a more hands-on shooter.