I was reading though the recent freebie copy of World Radio News today, and someone had written in asking how "we could rid the HF bands of AM" !!! They didn't publish the call of who asked the question. The issue is at my office now, so I can't provide the page number, but it's in one of the "ask your question" sections.
At any rate, the answer was to have a change in the FCC rules, and that it would be easier said then done. FYI -- 73 Mark K3MSB