It doesn't seem that Qualcomm will release the Nuvia cores with the 8cx Gen 4 / 8 Gen 3.
However, would be the first time that ARM-based compute chips arrive with the latest core desings, the 8cx Gen 3 arrived with an already old Cortex-X1, on an underperforming Samsung 5nm node (when 4nm was already available).
Mediatek pressuring and using the latest Cortex-X4, even if only for Chromebooks, would help to increase competition and pressure Qualcomm to stop using old desings for their compute offerings.
MediaTek is reportedly developing a new SoC with four Cortex-X4 and four Cortex-A720 cores. It is manufactured on TSMC's N4P node and could compete with next-gen laptop offerings from Apple and Qualcomm.