A 'new Newton' doesn't even make sense.
The only thing the touch/iphone lack, compared to a newton, is apps.
You don't need a different form factor for that - you need a change of philosophy. And that is one change I do not see coming down the pipeline.

If they were going to make a proper platform, they'd be better off with a subnotebook-sized multi-touch tablet running full OS X. At least that wouldn't cause as much confusion in their device topology. Lord knows they already have one head-scratcher in the form of the iPod touch. (I still have no idea who that thing is supposed to be for)

Any iPhone (<spit!>) based Apple PDA will also lack a proper stylus-based touchscreen. The Newton's forte was stylus operation, it won't even register finger presses.

The Newton's "metaphore" is a paper notepad, its entire user interface is geared towards that. You can't simply replace the stylus with fingers and claim "New Newton" (imagining for the moment Jobs would be stupid enough to commit intellectual harakiri that way).

Weirdly enough, OS X apparently allready has everything in place to become the O/S of a tablet: Inkwell is the evolutionary offspring of the Newton's HWR and those who have used it on an (illegally installed) Intel tablet, claim it's very good.

If I even liked OS X, I might have done the same thing; I have a tablet and everything needed to install OS X on Wintel hardware. But who knows, one day some dude might warez/hack Inkwell to run on Linux. I will not hesitate one picosecond to violate Apple's intellectual property rights to get such a doozy on a Linux tablet...