IMHO QF will not operate flights to DXB for a number of reasons.
Primarily they couldn't make money competing with EK's low cost structure, specifically the labour costs of the DXB hub. This is exacerbated by QF's lack of oncarriage from DXB. They would actually be helping EK by providing more customers to their hub for distribution on the network.
As well as this EK could then use the argument that they had offered QF all the fifth freedom rights in the world and surely Australia should reciprocate not to mention the fact that EK sponsor horse races, footy teams, arts festivals and so on.
On the other hand if Jetstar International could lower it's labour cost base in general and specifically by basing crew in Dubai, using DNATA or a competing handling company, setting up an offshore company based tax-free in Jebel Ali, tying it to the Oz network by operating A330s from SIN to DXB and then operating into Europe and India, they might be able to really change the nature of the SQ, QF, EK dynamic.