Technically "Airbus hasn't sold an A320 in three years." isn't right about the A319 as there have been orders the last three years, agreed no one wants it though.

Most A319neo orders look to be modified to be A320neo orders, so customers moving to a larger jet - perhaps it's cheaper than cancelling and buying Bombardier/Embraer. Or there is no demand for small planes in the ~120 passengers class.