Hahahahaha, I really had a nice time reading this thread.
I think, like many others, that the main attractive of the 500 class is that those monsters were hard to ride fast, and only a couple of talented rider could use them to their potential. But they dropped the classs and leave the 250, that need also some skills to get them on the pipe all race long. But they came with an easier to ride bike, the 450 4S. And here is the point that put a couple of nails in the 2 stroke coffin, this bikes are faster, but easier to ride, even someone without that much skills can ride one to a pretty fast pace. And thats why the crash rating grew, because people that doesen't have the skills where riding this open class bikes like if they where racing a cadillac el dorado rather than a racing machine.
So now thw 450 is still too much, so go to 350. Maybe this will be a little harder to ride, cause you have to ride them on the edge to fight the 450 on their ground.
I think that this move would make more money on maintenance and replacement parts, but also on aftermarket parts, cause if you cant use all the potentiall of a 450 there is no reason to put a hot cam and a full exhaust on it, but to be competitive on a 250, were you will squeeze every hp on the engine, you'll need every part and preparation you could afford to bet the guy next to you.