While thought-provoking, I suspect most cash-strapped AM broadcasters would prefer to NOT have to spend more money on new equipment to move to VHF. Most AM stations are progammed straight from the satellite to save money that otherwise would have to be paid for "air talent" and board operators. And the owners are still just getting by.
So interesting yes, but not likely. At least not in our lifetimes!
America needs a sense of humor...