Although a formation-flying space interferometer designed for exoplanet spectroscopy is feasible in principle, the novelty and cost of such an instrument is likely to remain daunting unless the scientific benefits of this technology are demonstrated by intermediary, precursor missions. Such instruments would represent intermediary steps in the real-life testing of the technology, and therefore, by the very reason of being intermediary, they may not have the resolving or collecting power needed for the study of the objects where biomarkers could be hoped to be detected, i.e., exo-Earths in the habitable zone of their stars. This paper examines the potential applications of such intermediary instruments. The direct line of thought focuses on exoplanetology (gas giants, protoplanetary discs, Neptunes, super-Earths, etc.); what we would like to stimulate is an exercise in lateral thinking, looking at what might an intermediary interferometric mission contribute to other fields of astrophysical research (galaxies, supernova precursors, planetary nebulae, molecular clouds, etc.). The paper raises the question of collaboration with astrophysicists studying areas other than exoplanets and its potential gains for the future of space interferometry.