What if's ? There are so many "what if's" with everything that if we are that worried about what might happen we should all lock ourselves in the house and never come out. Thinking like that and believing it is just more fear mongering .
As far as flying high near an airport , there is already an FAA regulation pertaining to operating anything RC related in that it must be at or below 400' plus if following AMA guidelines one always gives right-of-way to full scale aircraft. The rules/laws already in place are enough and we don't need any more.
If there was some kind of law mandating every person attain a certain level of common sense and courtesy by a certain age we wouldn't be having these issues.