here's how I think they're gonna do it:
In 2012 or 11, they're going to release the 5.0 in the GT and the ecoboost in the, as I'll call it, "SVO" (even though they won't name it that lol). Then, they'll keep a regular V6 in the regular Mustang.
The 4.6 will be dropped.
A gamble? Sure, it'd be one. But the term "5.0" is better for marketing just because the Boss 302s of the 70's and late 60's and the Foxes of the 80's. I mean, you really think all those people know what that stuff is? No way. They're in it for a name.
But yes.. I can easily be wrong.
Plus I'm using my grandad's logic for this one lol.