MATISSE and mid-infrared interferometry at the VLTI post-2030

Based on what has been achieved with the second-generation interferometric instrument MATISSE, we provide a plan for the future. Within the context of the ELT, and in particular METIS, the support of extending ground-based mid-infrared capabilities is critical. Possible upgrades to MATISSE are wide-field observations, metrology for phase referencing for improved sensitivity, upgraded detectors, a combination of the AT and UT telescopes for improved uv coverage, and the combination of observations from the ELT and VLTI. Because of the large apertures required for sensitive observations with respect to the thermal background, an evolution of the VLTI infrastructure involving a fifth UT or larger diameter ATs with longer baselines naturally pushes us to a new instrument combining more than four telescopes. In this contribution, we present several possibilities for expanding the realm of high-resolution science cases in the fields of active galactic nuclei, young stellar objects and evolved stars, with an active element on discussions for stepping into the next era of high-resolution astronomy together.