Battleships have been just a masturbatory fantasy ever since 300 planes sank the Yamato.
Tey weren't a fantasy in Vietnam; they were an extremely effective platform.
Grow up.
Combined arms are needed more now than ever.
They are expensive to maintain.
But I would recommend gutting their engineering plants, installing gas turbines, and make them both fuel efficient and allow gs types (not boilermen) to have a chance to serve on the Battleships..
Maximum ordnance on target is what will be needed often and repeatedly.
Getting rid of these platforms would be a mistake.
If all we were talking about was ship-to-ship combat, you'd be right. But since the great percentage of the world's population, trade, and resources are located within 22 miles of the coast (16" gun range) the Iowa's would still be extremely effective.
As to their expense to operate, the best overhaul would be replacing the old steam boilers with gas turbines. A nuclear powered ship would be even better. The crew savings would pay for the upgrade.
In a blue water fight with an adversary like Japan, you'd be right. That's highly unlikely to ever happen again. For the kinds of adversaries we do figure ot have in the next two or three decades, the Iowa class ship is far and away the best thing in our arsenal. Nothing much short of a direct hit with a nuclear weapon can do much damage to one of them, they can hit eighty percent of the targets we'd ever want to hit, and they can hit them as hard or harder than a carrier could in any kind of weather, with no risk to pilots. That's unbeatable.
Hardly the first battleship to be sunk by airpower...
BTAIM, an BB is the only ship that could survive a near miss by a nuclear missle. They don't (can't) make them like that anymore.
We'll have a little more to worry about than one battleship if we're facing any adversaries that can field 300 aircraft essentially unopposed over the Iowa today.
But you just wanted to use masturbatory in a sentence didn't you? ;-)