Probably Great Option for Pointy End Punters
I'm guessing a PER-LHR route will be quite popular with those fortunate enough to be able to travel in J class. Time moves (too) quickly when you are comfortably tucked in to a lie flat bed after a nice meal and a few drinks.
Whether originating in PER, or some other Aussie port requiring only a domestic transfer, there are MANY who would prefer to avoid the Middle East in order to get 1-stop access to the UK.
Regular punters in Y class? I'm not sure 9-across economy seating for 18 hours will be as popular. As others have suggested, probably more comfortable, especially with kids, to break the hideously long journey somewhere closer to half way.
If you're going anywhere else in Europe other than London, then the EK (and to a lesser extent SQ) connections can't be beat. Transferring and backtracking via LHR in a sleep deprived state is no one's idea of a fun day out.
Here's hoping it goes ahead, if for no other reason that it will create a bit of buzz and excitement in an airline that has become more and more like a travel agent in recent times. It's high time for a bit of bold behaviour!
PG