ORIGINAL: Mike in DC
My guess is that it will become impossible to keep the insurance business afloat, and that the folks who fly really big models are going to have to consolidate into some very isolated fields where spectators assume some of the risk. If I were king for day, and I wanted the AMA to last into the future, I think that rather than trying to keep the insurance program viable, I'd be trying to get out of the insurance business. Otherwise, it's just waiting around for the next big claim that wipes out the organization. (Google "nspi bankruptcy" for an example.)
I would rather try to keep the AMA intact with insurance, but I see your point. If you ask me, an AMA structure that could exist into the future (without insurance) is of little use to me, and I would hazard that it would be of little use to maybe 75% of everyone currently in the AMA. The hardcore fliers would create a new organization dedicated to insurance, and have a lot fewer fields to fly at at a much higher cost.....it would be just as easy for the AMA to stay intact and admisiter the insurance. And if one big accident happens, heck it was always possible, why not ban all spectators and have all AMA members indemnify each other? Might get to that someday, who knows.
I will repeat, I do think that (some) park flyers might eventually go to the AMA once they start loosing sites (and they will loose them, if California is any indication). I also think there might be some new 'electric only" AMA charter clubs that start cropping up to exploit this new technology.
Personally, I am not opposed to tiered rates. I think if a WORKABLE system can be developed, it would at least be worth a try. Unfortunately, I think a workable system is going to be very difficult to come up with.
But like I said, I am open to it. If insurance is the MAIN reason that most still have AMA, IMHO it is the ONLY reason you will get a park flier to join, until they need a field.