  A brief review is given on the physics potential of HERA beyond the presently
approved programme. Questions of particular interest include QCD in a regime of
weak coupling and high partonic densities achieved in eA collisions and spin
physics with polarized colliding beams. Those two distinct programmes can be
naturally merged and even substantiated by using polarized and unpolarized
deuterons at the starting phase of the HERA-3 run. Basic machine implications
and detector requirements are also discussed.
