My favorite line from "The Right Stuff" is "No bucks, no Buck Rogers." Today, NASA is facing about a $7 billion funding shortfall. Something has to give. Depending on the funding levels, there simply may not be enough money to develop the methane engine(s) in the near term. That doesn't mean they'll never be developed.

As it stands, it doesn't look like the CEV design is suitable for a Mars mission anyway based on what Gary said about the heat shield design. NASA may be forced in the near term to use off-the-shelf technology to go to orbit and perhaps to the moon. There will still have to be a lot of development before they're ready to go to Mars and that isn't likely to happen for another 15-20 years. There is plenty of time to develop the methane engine. Now, if there's only the money...