Floating, remote operating bases that can move to provide persistent support are still pretty important if you want to hold territory. Long-range missiles can hit an objective, but I'm not sure we really have long-loiter-capable assets to just go around in a circle and provide a similar capability to a carrier. Furthermore, I can't imagine the cost of some future-whatever RAMjet craziness that would get closer to carrier-level strike times, but I'm just an armchair strategist. A cost comparison would certainly be interesting!