Both sides of government have been looking at tax reform for the last five years. The problem is we have become so soft as a nation that anything that hurts us the tiniest bit financially results in outrage. The political cycle is now determined by polling. There is no such thing as vision or being prepared to do the unpopular thing. It is stay in power at all cost.
Like it or not negative gearing is on borrowed time. It is all about perception and the perception is that it is a policy that looks after older people at the expense of the young. That it is a policy that makes the already wealthy even wealthier, while the young are left to deal with the world's most expensive housing. I have heard both sides of the argument and am fairly ambivalent but at some point the demographics will change enough that ng will be scrapped. It could be next year or in 10 years but you only have to look at the rise of someone like Bernie Sanders to see where politics are headed. There is starting to be a very noticeable political wedge between the young and old in regards to things like social democracy and inequality and the cost of housing is probably the sorest point.
I don't think Bill Shorten is stupid to back scrapping negative gearing. He is already pretty much doomed anyway. He is positioning his party to try and prevent it becoming even more irrelevant to young people who are increasingly looking to the greens.