In the last decades, performing arts have undergone a profound transformation, driven by the integration of new forms of participation and emerging technologies such as eXtended Reality (XR). By merging real and virtual spaces, XR challenges traditional notions of presence, embodiment, and spectatorship, transforming the audience from observers into participants and co-creators. This paper explores how XR is contributing to the reconfiguration of the language of the performing arts, with a particular focus on theatre. Through a theoretical discussion supported by selected case studies, this work highlights the main conceptual nodes emerging from the encounter between corporeality, performance and digital elements. The paper concludes by reflecting on the necessity of maintaining a balance between technological innovation and artistic integrity, and points to future possibilities for XR in performance, particularly in conjunction with Artificial Intelligence to further personalise and expand the interactive experience.