  Supernova remnants serve as nearby laboratories relevant to many areas in
Astrophysics, from stellar and galaxy evolution to extreme astrophysics and the
formation of the heavy elements in the Universe. The Chandra X-ray mission has
enabled a giant leap forward in studying both SNRs and their compact stellar
remnants on sub-arcsecond scale. However, such high-resolution imaging studies
have been mostly limited to the nearby and/or relatively bright objects. There
is no question that we are missing a large population, especially in external
galaxies. Within our own Galaxy, we are presented with new fundamental
questions related to neutron stars' diversity, kicks, relativistic winds and
the way these objects interact with, and impact, their host environments. In
this white paper, we highlight some of the breakthroughs to be achieved with
future X-ray missions (such as the proposed AXIS probe) equipped with
sub-arcsecond imaging resolution and an order of magnitude improvement in
sensitivity.
