According to a report from Automotive News, Koei Saga, senior managing officer in charge of powertrain development of the Prius, said in an interview last week, "I think we will possibly do [all-wheel drive]" for the car's next generation. There isn't any further indication on how the AWD system would work, but we'd put our money on something similar, at least in principle, to the E-Four system that just debuted on the 2015 Lexus NX 300h, which uses an electric motor mounted at the rear to power the car's back wheels when the front wheels lose traction.
The AN report also repeats a rumor we've heard before – that Toyota may offer two different battery pack options in its next Prius, one using lithium-ion chemistry and one using the nickel metal hydride technology that the Prius has featured from its very beginning. While the automaker has yet to talk efficiency, it's natural to expect more capacity for EV driving from newer lithium-based technology over that of nickel-based packs to go along with what we'd also expect would be a somewhat higher price.
We're sure you're just as curious about the next Prius as much as we are, and so we'll leave you with these words, again from Saga: "The batteries will be renewed. Everything will be revised. And I think we will come up with a fuel economy that will surprise everyone."