This is according to an announcement by Wilcox on his LinkedIn page in which he will be taking up a new position at Intel as an Intel Fellow and will be the Design Engineering Group’s CTO. Prior to this, Wilcox had worked as the Director of Mac Systems Architecture at Apple for the past 8 years.
He helped to oversee system architecture, signal integrity, and power integrity, and was also instrumental in helping Apple transition over to Apple Silicon. While it sounds like Intel might have poached Wilcox, it should be noted that prior to working at Apple, Wilcox actually worked at Intel first and had a short stint at NVIDIA, so if anything, it seems like Wilcox is more like returning to Intel.
Whether or not Wilcox’s departure will have any negative impact on the future development of the Apple Silicon remains to be seen, but presumably Apple already has plans in place to deal with employees leaving.