Let me ask you this, if the Mustang is such a paltry competitor, then why is Ford not on the verge of bankruptcy? It works.
The Mustang has had no competitor since 2002 or whenever the Camaro croaked. There wouldn't even be a new Camaro if it wasn't for the S197's success. That is the reason why the 4.6 lasted as long as it did, because there was no need to upgrade.
Now with GM's LS3 that they seem to throw into everything, Ford is bringing back the 5.0. Don't even pretend that its not going to be a reality. Just do some research.
Plus, look at the new 2010 mustang test from Motor Trend. The car stops in 108 ft, pulls 0.95g on the skidpad, and accelerates to 60 in 4.9 sec. It even does a 13.5 quarter with this archaic engine that you talk about. This all with $1495 track pack. That will only improve when the new, LIGHTER, 5.0 comes out. If a 5.0 is not your thing, then you have the 3.5L Ecoboost producing 365hp. Talk about a tuner's dream with all forged internals and direct injection to boot. This engine will be even lighter than the 4.6L
I'm sorry to burst your bubble, but there is a reason why the Mustang has never ceased production. Its fast, fun, and affordable. Now