Tom King went on Twitter to address the reason he’s not writing Batman #64 or 65 (both February 2019). A “secret” TV project will keep him occupied until he returns to the Dark Knight in March; it’s unknown whether this is the previously announced States of America.
Joshua Williamson will fill in during the Batman-Flash crossover. King’s absence will also extend his Batman run past #100.
King’s final tweet on the subject summed up his feelings: