I think there's been some good arguments here both for and against Ten launching late news.
A large part of the reason the 9.30 slot rates so poorly these day isn't because no one wants to watch TV, but more because there's nothing people want to watch. This is largely because reality and drama draws different audiences, although some of the audience is the same, so it's hard to get good follow on of audiences through the night.
News might be different and draw in new audiences and retain the audience better, but other viewers would be lost. Realistically viewer numbers and ad revenue aren't going to charge all that much, and any increase comes with a huge risk- both news and imported dramas are expensive, but it's a lot easier and cheaper to cancel a show that you don't have to produce yourself if it doesn't work out.
As much as Nine and Seven are investing a lot in bulletins at 4pm, with low ratings, these are designed to draw in viewers for the rest of the night. They hope that once someone tunes in they won't change channel until after the 6pm bulletin or even prime time - are largely that is true. It's also turned into a highly competitive time slot, so the networks will happily spend more money there than in a non competitive slot with no follow on benefit.
TEN would be better off to focus on the 6am-8.30 slot. Whatever they have there, be it news or otherwise, needs to draw viewers away from 7&9 to help get viewers follow on to Studio 10. That way any investment they make gives a secondary benefit in boosting Studio 10's numbers as well.