The race between Aerojet Rocketdyne and Blue Origin heats up. But as noted in comments over there, there’s a big word missing in the story: Reusability. And the issue isn’t so much reusability of the engines themselves (though I’ve heard nothing to indicate that the AR1 will be reusable), but in the vehicle design. ULA does not want to continue Atlas with a new engine; they know they need at least a recoverable propulsion/avionics unit of Vulcan to even hope to be competitive with SpaceX (and Blue Origin).