  We present results for $B_{(s)}$- and $D_{(s)}$-meson semileptonic decays
from ongoing calculations by the Fermilab Lattice and MILC Collaborations. Our
calculation employs the highly improved staggered quark (HISQ) action for both
sea and valence quarks and includes several ensembles with physical-mass up,
down, strange, and charm quarks and lattice spacings ranging from
$a\approx0.15$ fm down to 0.06 fm. At most lattice spacings, an ensemble with
physical-mass light quarks is included. The use of the highly improved action,
combined with the MILC Collaboration's gauge ensembles with lattice spacings
down to $a\approx0.042$ fm, allows heavy valence quarks to be treated with the
same discretization as the light and strange quarks. This unified treatment of
the valence quarks allows (in some cases) for absolutely normalized currents,
bypassing the need for perturbative matching, which has been a leading source
of uncertainty in previous calculations of $B$-meson decay form factors by our
collaboration. All preliminary form-factor results are blinded.
