I don’t expect any upgrades. Except maybe related to software in the audio, navigation or OnStar.
Escalade will get optional supercruise.
There will be a few paint color changes.
There will be some decontenting. Expect optional wheels to be reduced in number. Wouldn’t be surprised if power sliding console is deleted in MY2022. Maybe some decorative stitching will be deleted.
Production changes under the skin will occur to facilitate vehicle assembly and improve initial quality.
Keep in mind that these MY2021 SUVs were intended for MY2020. They were pushed to allow more development time. But CY2020 was disastrous for all manufacturing. So far CY2021 isn’t looking any better.