Chuck Alaimo,
I was simply speculating on the sustainability, given what appear to be some pretty significant market pressures that may be just around the corner (Pressures, by the way, that are self-inflicted by these two companies if they really do elect to release low-cost full frame models.)
I don't seem to find any correlation of what you've stated vesus the title of your post: "Is the 5DIII the New 50D?"
This is the start of a D600 vs 5DIII thread hijak where Canon are stated as money grabbing with inferor products 
i'm really disappointed that you forgot to mention the substandard DR of canon and blah blah blah
yeah its all getting a bit old isn't it?
Indeed.
I am waiting for the naughty forty to arrive on Monday - then I should be able to use the 7D as a street camera.
I do agree about the 5DIII getting a bad name, but it seems mostly to be based on forums with a large North American group of users. UK based sites are all singing its praises, even with the odd hitch here and there - they dont seem to care about the light leak as it didn't impact their images
My 5DIII owning friend had to send his back to Canon for 'adjustment'. Took 4 days to do (from posting to return). He is now producing stunning pictures with it. His pictures with a large white show just how good it really is - I would say basic IQ is as good as the 1DS3 (although I still prefer the 1DS3 colour rendition and low noise at iso 50-200)
He upgraded from a 50D - and is blown away by it.