I'd like to see them offer these engines:
Entry/economy model: EcoBoost 4-cyl (270bhp)
V6 model: add DI to the current V6 or do an EcoBoost V6 (both around the 350bhp)
GT: add DI to the current 5.0L (around 450bhp)
That engine lineup, with a 200lb weight loss across the board would be nice (even more weight loss would be nice, but I'm being realistic).
I couldn't care less what they do with the GT500 as it is well out of my price range.