The "winter window" here indicates bookings are not looking the best.. Prob only QLD would be doing well. Business travel is coming back but still well down I would say.
The only curious thing for mine about the promo is more the audience. I mean Points CLub (and Plus) is supposedly designed for those that earn in ways other than flying. Now granted these covid days that's the vast majority of us (and this may be the key here), but in general these folks probably do not normally rack up many flights normally.. so trying to tempt with status credits is.. confusing? If you're a heavy earner via spend (let's ignore card churns and the like) you may earn those points with the notion to redeem for "big trips" - probably OS for the family.. and that's not happening now.. but throw a DSC promo with a 3 month-ish period for travel seems odd to me.
I can only conclude that this is probably seen as a token/cherry on top promo for QF with little cost to them and potential gain in closer in/short term bookings during a slower period in winter for all but "sun destinations" (or ski if you like). I mean it looks great to "celebrate" the changes with a promo but the target audience probably won't be booking more than usual anyway.
As above though, given most of us may have wound up at PC level but had relatively few flights, we may or may not book, but I doubt the prom is the driving stimulus here (specially with a 3 day booking window which is shorter than most)
in summary I reckon take up would be modest and QF is most likely fine with that.
in the bigger/medium term I fully expect there will be more bonus SC promos so those feeling left out or whatever... worry not. The longer this mess goes on, maybe for another year or more again, QF will be forced into extensions/support again and promos. Gee I'd hate to be working in the planning and marketing/loyalty areas right now it must be a nightmare with ever shifting goal posts, projections regularly thrown out the window and many "Well what do we do now????" meetings.... I imagine.