I'm not so sure it will happen here. Not that NOx pollution science is disputable, but it's all about NOx concentrations and Sydney is fairly fortunate in that ocean breezes refresh the air over half the populated areas almost every evening. The Western suburbs aren't so fortunate, but there's not so much traffic congestion there despite the huge number of cars.
We haven't had CO2 taxes on fuel, and as a result the number of diesel cars per total registrations is half of what it is in the UK. Petrol is also fairly cheap here, and as diesels are a more expensive engine on outlay that forms a barrier. Honda didn't bother selling a diesel engine here until 2013,and then only sold a few hundred DTEC CR-Vs. I think has since withdrawn the diesel engine from the AU market due to poor sales.
That said, I think that diesels will probably disappear from available engine lines as HCCI engines take over the IC market. (with EV's making up the rest) This might take about 20 years, but NOx will probably go the way of Tetraethyl lead.