We sold out but only after it went to general sale. You can check last season's ticket announcement and the last seasons announcement when it sold out to xref what stage it sold out at. It was right at the end of the sales process.
Can see it not selling out depending on criteria (if sale completely open Villa will buy) - £72 for a bad view and the 3rd time in a row, or 5th time in 7 years will put some off. Normally we have 5 going, this time only 3, and while that is a pathetically small sample to base anything on, I can see it being typical.