Conor is sponsored by big name companies, just did a milli on PPV and they had to add in seating for 189 because of the demand.
The UFC got 19k in Dallas in 2014, and yes I am aware they had 5k less than this year in Dallas. However the difference was local hometown boy Johny Hendricks was not main eventing for the title like the previous Dallas card, and Johny was a hotter name at that time.
If they can get 19k with Hendricks for the title, then with Conor vs Aldo + Ronda and whatever else they add on (possibly a 3rd title fight), they can potentially do well. You also stick that card during the holidays (Friday January 1st could work) which makes it easier for more people to travel (like the Irish but also fans from all over).
Depending on how they price out the tickets, it is not an inconceivable idea that they could pull in 60k.