I'm surprised the Virgin Sydney flight lasted as long as it did. The Europe - Australia route has long been a bloodbath for the European based airlines and Qantas. For years the Asian carriers and more lately the Middle East carriers have been progressively taking over that market with their lower costs, more attractive schedules and better service. Airlines like KLM, Lufthansa, Air France / UTA, Austrian / Lauda, Alitalia, Olympic, JAT and others have already stopped operating the Australian routes in their own right. Some have disappeared altogether whilst others now codeshare on the very airlines that replaced them.
The way Qantas are going it won't be long before their last two Europe flights into LHR are replaced with Emirates tails, whilst BA are now down to a single token daily 777 to Sydney.
All part of the trend towards globalization and alliances, which Virgin appear to have finally caught onto with their tie up with Delta.