I'm actually thinking there will be a 4 cylinder option on the list. Considering the Mustang has the 2.3L EcoBoost, the Camaro now has a 2.0L turbo engine as well. I think it'll make sense for the Cuda to come with a 4 cylinder option for those that want the show but not the go, although it is possible to squeeze quite a bit of power out of them.
I wouldn't mind seeing a Hellcat engine in the next Cuda. That engine is capable of pumping out 700hp so long as the vehicle can handle it.
Doubt they would take on that approach since so far it seems this could be more of a laid back coupe. some are suggesting it will be more GT-like or on a slightly smaller platform in between an FR-S and Challenger.