"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Low Power G5 Coming Soon?
Additionally, a low-power-consumption version of the PowerPC 970 is expected to emerge for use in the upcoming PowerBook G5. The chips are expected in 1.6 & 1.8 Ghz variants, although not much more is known. The article goes on to say that if the 970GX is not ready for a PowerBook G5 introduction, that model may receive the low watt, high output previously rumored PowerPC 7448 G4.