Since we just speculating, why not as an optional upgrade to the base V6? Kind of like the old GTS model niche. Matter of fact, at 250HP, it would more powerful than the 5.0L (that had just 215HP??) offered on the old '95 GTS model.
I'm just glad to see the old 3.8 is being replaced with a more modern power plant. The 3.8 wasn't a terrible engine, but it was really starting to show its age.
The 3.8 has already been replaced with the 3.9, as a mid-year 2004 change. It still surprises me on how quitely that was done. Even Mustang watchers, and the BON rumor mill, didn't know until they were found on dealer's lots.