  Hi-5 is a high-contrast (or high dynamic range) infrared imager project for
the VLTI. Its main goal is to characterize young extra-solar planetary systems
and exozodiacal dust around southern main-sequence stars. In this paper, we
present an update of the project and key technology pathways to improve the
contrast achieved by the VLTI. In particular, we discuss the possibility to use
integrated optics, proven in the near-infrared, in the thermal near-infrared (L
and M bands, 3-5~$\mu$m) and advanced fringe tracking strategies. We also
address the strong exoplanet science case (young exoplanets, planet formation,
and exozodiacal disks) offered by this wavelength regime as well as other
possible science cases such as stellar physics (fundamental parameters and
multiplicity) and extragalactic astrophysics (active galactic nuclei and
fundamental constants). Synergies and scientific preparation for other
potential future instruments such as the Planet Formation Imager are also
briefly discussed.
