Re younger demo - I think QF will need to do something re mobile phone plans, internet plans, home loans etc ... the younger demo are more hooked to these businesses/services.
I remember Vodafone did something for QF points a while back, unsure if it is still on though
For instance, I'm 30 and I'd be happy to sign up to a mobile/internet plan if QF is giving sign up bonuses etc and I will be soon taking out 2x home loans, so I'd be happy to sign up for a QF point earning home loan provider, if there is some benefit for me