Don't be too excited, I have been on plenty of "all 0s" flights, expecting an op-up, and there are actually empty seats in Y.

Like another poster said, they may be stop selling across the board because they have no where to op-up people to, and the safe thing is to not sell seats rather than oversold and no where to put them, and then you have to give compensation, arguments, get them on another flight, etc. etc.