I don't think any of us will be surprised...this is what I expect:
GT - 5.0L 400HP with a 6spd manual finally offered. Probably will pick up some weight but still won't be a cow like the Camaro.
V6 - 3.7L 280HP....not sure what transmissions will be offered.
GT500 - 5.0 Supercharged, better tires and
suspension for improved launching.
I'd be more surprised if they didn't have these offerings.
The GT and V6 offerings will put the Mustang into Camaro territory for HP and being that it's a lighter vehicle with a live axle as long as the tires can hook up I'd go ahead and bet that in the next comparison of the muscle cars it won't even be a competition anymore seeing as how Mustang already won overall value this year with an engine that's about 15 years old and a log axle out back that does it's job better than the fancy IRS in the Camaro. Not to mention the interior of the Camaro....further proof why GM can't get its act together.