Nor does the Pentagon really want a fast-tracked rocket engine, says Marco Caceres, senior analyst and director of space studies at aerospace consultancy Teal Group. "The engine is the core of your rocket, and the majority of things that go wrong in a rocket have to do with the engines," he says, "You really don't want to rush this."

Moreover, the Pentagon plan intends to spread the cost of technology development out via public-private partnerships, each of which would require roughly a dozen private sector space launches each year to remain viable. That launch demand doesn't yet exist, nor does a spike in demand appear on the horizon.

All that places SpaceX in a particularly good position to take on a lot, if not all, of the military's space launches toward the end of this decade, at least until other launch technologies can be adequately matured. Barring a change in Congress's stance on RD-180 imports or some kind of mishap that jeopardizes its certification, SpaceX might not just break ULA's military launch monopoly—it may become the monopoly.

"Overall, SpaceX is starting to look very all-American and very attractive, and ULA looks weak without its Delta IV," Caceres says. "All along ULA has had its eggs in one basket, but that only works as long as you've got a monopoly."

"This is huge," said Marco Caceres, senior analyst and director of space studies at Teal Group. "It would break up a monopoly and has the potential to save the taxpayer an awful lot of money."

"The writing's on the wall for Atlas V as a launcher," said Marco Caceres, senior analyst and director of space studies at Teal Group in Fairfax, Virginia., a firm specializing in aerospace and defense market research. "We cannot rely on the Russians over the long term. And from an economical standpoint, Atlas V is still too expensive the way it is to compete against emerging companies like SpaceX, and certainly to compete successfully in the commercial markets."

 The announcement put as positive a spin as possible on Gass' departure, but reading between the lines makes it clear leaders at the parent companies felt a change was needed, said Teal Group analyst Marco Caceres.

"Gass hung his hat on ULA's track record of successful launches," Caceres said. But ULA looked complacent when matched against the dynamic Elon Musk, whose SpaceX will shortly begin competing with ULA for military space launches.

Caceres said he expects to see layoffs and a streamlining of ULA to find all possible cost savings.

"My sense is you're going to see at ULA a restructuring of some sort, because ultimately they're going to have to find a way to be a lot more competitive on price," he said.

And the RD-180 has its supporters. "There's nothing out there that's better in terms of weight-to-power ratio than the RD-180," said Marco Caceres, an analyst with the Virginia-based Teal Group. "I don't know if you can come up with an engine as powerful as the RD-180 in a short time from scratch. "It's really more about developing the least expensive engine that will make the Atlas V much cheaper commercially."