I agree would be a data exercise to see how many people do actually bite, and in turn depending on their uptake will offer it more broadly in the future maybe.
I have a feeling the number was closer to 15000
I think QF might be doing a few things with these offers ;
1. Look how many people are biting into the offers
2. Of those who took a bite, how many are actually making a booking ?
3. Look at how much $$ is spent/person - this could help QF forecast revenue
4. Of the $ spent, how many people booked into premium cabins just because of the DSC.
I say this because, QF has been releasing a lot of offers over the past 4 weeks. First we had the 50% SC, then Premium Cabin companion sale, had the NT/Domestic cities sale in parallel, now the DSC. I think the take away from this DSC offer would be to see how many people, who started to make a booking during the 50% or NT/Dom sale but didn't do it and check if the DSC has pulled them in and how many of those who would usually book Y have now booked in PE/J/F
5. To check if people are responding to these offers, by means of registration or booking a ticket or even attempting to make a booking
6. Try to squeeze in funds before Christmas, because after Christmas and until early Feb or late Jan, people might not have money to spend. And I think this is why the travel date for the 50% SC and the DSC are well into 2020. People would go "Oh look, the travel dates are well into 2020, may be we should lock that holiday"