As AI takes on increasingly complex roles in human-computer interaction, fundamental questions arise: how can HCI help maintain the user as the primary agent while augment human cognition and intelligence? This paper suggests questions to guide researchers in considering the implications for agency, autonomy, the augmentation of human intellect, and the future of human-AI synergies. We observe a key paradigm shift behind the transformation of HCI, shifting from explicit command-and-control models to systems where users define high-level goals directly. This shift will be facilitated by XR technologies, whose multi-modal inputs and outputs offer a more seamless way to convey these goals. This paper considers this transformation through the lens of two cultural milestones: the personal computer and the automobile, moving beyond traditional interfaces like keyboards or steering wheels and thinking of them as vessels for everyday XR.