ORIGINAL: Thor77
I don't know if current CVT technology would even be able to handle the kind of power that the Challenger is projected to have. So far they've been fairly limited in terms of the torque they can transmit because of their design (relying on chain or belt drive).
It's hard to say for sure. The most powerful output on a somewhat conventional car is in the Lexus 600h with their "ECVT." The combined output of the gasoline engine and electric engine is around 438hp & 385 ft-lbs of tq. This in theory could be able to handle a 5.7L's hp output, but the torque output of this Lexus is still below the 5.7L's. The 6.1L would really be pushing their luck considering that there isn't very much room between the 6.1L's hp output (not to mention that it is proven to be underrated and really produces around 467hp) and I really doubt that it could handle the 420 ft-lbs of torque either. There is probably no way it could handle any of the other rumored engines though. The real question though is how long could it handle this level of engine output. Just because it won't break right off the bat, doesn't mean it would snap after being stompped on enough times.
Beyond any of this, cars that offered CVTs as options have historically not done well. The Ford dropped that option out of the Freestyle and the Five Hundred/Taurus as they were not a well accepted item. GM tried for a few years with the Saturn Vue and Ion and ended up going back to a 4-speed auto. If you look around you'll see that they just haven't been a popular move to make. I say try the dual-clutch route or figure out a way to make a performance minded spec version of the 68RFE. That would have more than enough torque capacity for needs of automatic drivers, not to mention towing for that matter.
