Go back and actually read what was said above. We arn't saying the base Cobra will be 500hp, I think we all agree it won't be more then 450hp, though it probibly will be atleast or more then 420hp so it can compete with the base corvette, base GTO, and (base?) 425hp Charger in 0-60 and 1/4 mile. The price will probibly go up, but I don't think it will go above $45,000, and it will definately stay less then $50,000.
Now however, in 2007 we will have a 500hp GTO Judge, a 500hp (Z06) Corvette, and a limited edition 600hp Corvette, not knowing what Dodge's plans are for a more powerfull Charger. The limited edition Ford GT will not be around anymore, as it will be ending its 3 year production. What looks like a 600hp limited edition will take its place based on the Shelby Cobra/GR-1 concepts (From what I have read the GR-1 concept is more affordable to produce then the Cobra concept and just like the original Daytona's is a better racer, so it may just be affordable enough to be a direct replacement for the Ford GT, though it's price will depend on Ferrari's prices).
Anyway, That means there is a large chance we will see a 500hp special edition of the Cobra inbetween the base SVT cobra/Shelby mustang and the Shelby Cobra/GR-1, which would be priced less then the new 500hp Z06 and around the same price as the 500hp GTO Judge. Now, being Shelby's first mustang with Ford was called a GT350, for Shelbys first mustang back with Ford it would make sense that it will be called a GT350. (which is supported by what I heard and read from many sources) This makes perfect sense if they are using the GT350 name for the base Cobra, as the GT500 name would a logical choice for a special edition 500hp Cobra (Special edition like previous Cobra R's were). It might even be called a GT500R in keeping with previous high performance racing Cobra's using the R designation in the past. That I can't tell you, but I can tell you with almost 100% certanty we will see a 500hp or close to it mustang unless something major happens (gas prices, new emmissions laws, ect).
It won't be a $40,000 car or even a $45,000 car, but I really do think it will be produced. It isn't like it will be that hard to make, possible engines are already there in two forms (Lightning and Ford GT), if they use the lightning motor it will be supercharged, if they use the Ford GT motor it might not be supercharged (maybe they will use the motor directly and instead of a 500hp Cobra we will see a 550hp cobra or maybe they would slightly detune it?). Logic says the base (400hp to 450hp) Cobra will be N/A (which is what I heard from the Ford guy at NY-AS), with the around 500hp cobra being Supercharged, but that is complete speculation that can change very easily depending on what motor they decide to use and how they tune it.
All we know for sure from the SVT guys is a future Cobra mustang will be an absolute beast compared to now, instead of GT500 the higher end Cobra mustang might even be called a GT350H if the base cobra is a GT350. That is another completely feasable option. The original GT350H was a two seater and both the Cobra mustang concept introduced to show off the 2005 mustang and traditional high performance Cobras (Cobra R's) were two seaters.