However the new Sydney service schedule is a Sydney - Darwin - Sydney service which touches down and departs Darwin in the early afternoon, whereas Silkair's Singapore - Darwin - Singapore back-of-the-clock service sweeps through Darwin in the early hours of the morning, 12 hours too early or too late to facilitate a connecting service.
So the new Sydney service appears to be targeted at taking on Qantas on their daily daylight service to Darwin.
Further comments on Virgin's Sydney announcement can be found at: CAPA and Australian Business Traveller websites.