A 500mm f/5.6 IS or 600mm f/5.6 IS in the $1500 range would be really nice. I wouldn't even care if they were L or not.
I think this is nudging into wishful thinking. A 500/5.6 is going to be only a little bit smaller and lighter than a 300/2.8, and a 600/5.6 would have to be close in size (same front element diameter) as a 300/2.8.
So I figure (optimistically) that a 500/5.6 would be 2kg and about $3400 while a 600/5.6 would be about 2.5 kg and $4200.
I still think there would be a market for these lenses, especially with wildlife photographers. When you look at the difference from these to lenses like the 500/4 or the 600/4, these would be a lot cheaper and a lot more portable.


