I wonder if they'll come up with airport MRI (which I think will show up anything hidden in body cavities). Implementation would be interesting and very awkward.
Would I consider it reasonable? NO. Would I be annoyed? YES, very annoyed with terrorists and also with the government if they made it a universal requirement because it would be potentially putting people at risk (what would the risk of having a full-body MRI five times a week for aircrew, for instance? The answer is, no-one knows!).