Tory Bruno, in an op-ed published by SpaceNews:
We’re making enhancements to Vulcan’s Centaur upper stage to add crucial heavy lift capability for the Air Force. That will add about six months to the program’s original schedule, but the resulting delay is months, not years, and it’s a purpose-driven change to deliver better performance, not a schedule slip.
The Vulcan-Centaur combination will permit launch of the nation’s heaviest satellites to any of the nine reference orbits our national security customers require. Moreover, the enhanced Centaur stage will allow this heavy lift capability without resorting to the costly three-booster configuration of today’s “heavy” launch configurations.
This is some curious new information. What we had heard previously was that Vulcan was going to fly first with today’s Centaur and wouldn’t be able to cover all reference orbits—which meant Delta IV Heavy sticking around. Eventually, Vulcan would move to ACES, which was a brand new stage packed with a ton of improvements, and would allow the retirement of Delta IV Heavy.
I wonder how many—if any—of those ACES improvements will find their way into this Centaur upgrade. Interestingly, ACES was not mentioned once.
Goodbye ACES, long live Centaur?