The 4.0l is the best 6 cylinder Jeep engine of all time. Our 01 Cherokee Sport with the 4.0l absolutely blows away the Pentastar in our Wrangler Unlimited. Unfortunately, I think the new smog regulations will never let the 4.0L be what it was with its great low end torque. The classic 4.0L with the new ZF 8 speed would be a dream.
I think the love of the 4.0 L 6 cylinder engine needs to slow way down. I had a '98 Grand Cherokee (much lighter than today's Grand Cherokee) with 4.0 Liter 6 cylinder engine. It was underpowered. The check engine light came on going up a hill. Much later on I found out it had a bad head gasket.
Maybe with the european influence it will be a 3.0 since 500cc per cylinder seems to be about the most common displacement for engines from that area of the world.
Unsubstantiated rumor time, I was picking up a new Charger Daytona 392 this week and while waiting for the paperwork was chatting with the sales manager. The new GC engines came up and I mentioned that it seemed sad there would likely be no Hemi option for the non SRT GC's. He said that what they are hearing is that the I6 will be 360hp and be very equivalent to the current 5.7....