  Lattice calculation of $B\to D^{(*)}\ell\bar\nu$ decay form factors is now
available from multiple lattice collaborations for both zero-recoil limit and
non-zero recoil kinematics. Yet, there are a number of challenges we face to
better control the systematic errors and to extend the application of lattice
calculations to related quantities. The subjects are chosen from my own
perspective and not meant to be conprehensive.
