Stansfield Turner has argued that the supercarriers might not be needed, and this led to some hearings from a Congressman.
Folks, this is the same Stansfield Turner who gutted CIA's HUMINT capabilities, from which the CIA never recovered - despite a brief resurgence under William F. Casey, arguably the best DCI that has ever served.
His track record is one that needs to be considered before we follow his advice.
That said, CVN-21... I'm unsure about. We're paying at least $14.6 billion for it ($5.6 billion in R&D and $9 billion per carrier). That's almost enough for three Nimitz-class carriers - or two Nimitz-class CVNs and thirty littoral combat vessels.
Maybe it is time to kill CVN-21 and the DDG-1000 (Zumwalt-class destroyer), and instead just build more Nimitz-class carriers and Arleigh Burke-class destroyers. IT's cheaper, and the U.S. Navy will have more of them.