My take on engines is that most if not all will be electrified. I may be wrong on this but CAFE and CARB are important... An who knows what will the next US President do with it.
So engine line-up may look like a:
- GME T4 D (DOHC) with 48 V BSG (Belt Driven Generator) MHEVsystem
- 5.7 liter HEMI with a 48 V BSG mild hybrid system or maybe without it
- GME T6 with a P2 (electric motor on transmission input) MHEV system and eBooster (electric supercharger) plus a turbocharger which takes up at higher rpm
Speaking about Hellcat. In my opinion even it can be improved with a system similar as on GME T6. In that case they will improve fuel economy by not an insignificant margin.
The most important part to reach CAFE could be a HEV and a PHEV versions. Yes, in the last 5 year plan new Grand Cherokee was highlighted as a one of just 2 FCA vehicles which will got a HEV version.
Basically it's the similar system as a PHEV for RWD based vehicles but without a plug and with a much smaller battery. I think that it can be more attractive to Americans than a PHEV. It should be different in Europe and China.
I don't know nothing about that system and whether will te be offered and with which internal combustion engine.
For PHEV I know that on Wrangler it will be offered with GME T4 D. AFAIK on all current GME T4 D and GME T4 M turbochargers are supplied by Honeywell but on this PHEV supply contrast is won by BorgWarner.