The Mustang has outsold the Camaro and Firebird combined for something like the last twenty years. GM has had Ford outgunned in the horsepower department for about the same amount of time. Ford hasn't needed to do something "really fantastic" to make GM compete, because GM hasn't been able to compete. Hell, the SN Mustang chassis is essentially the same thing as the Fox chassis which came out in 1978. And even back in 1978 the Fox chassis was little more than repackaged Fairlane bits.

Ford is strapped for cash right now so I wouldn't expect miracles out of the next Mustang. Its been widely known for quite some time now that it will be built on the DEW98 platform like the article mentioned. The motor choices sound appealing and assuming they get the chassis tuning right, it might even be worth comparing to the 350Z. Is that "fantastic" enough for ya?

Edit: the terms "muscle car," "refined," and "reliable" should not be used in the same sentence unless the term "not" is also involved.