Yes, you can be sure there's a GST increase coming when the treasurer goes out of his way to downplay it or put it into 'context'.
I'm reminded of a Kiwi Dairy Farmer mate who said that when GST was introduced at 10% even the dumbass dairy farmers could work it out. When it went to 12.5% everyone had to buy calculators. It now sits at 15%.
Given Australia's burgeoning deficit and shrinking tax base, it's inevitable. It might be a slow burn to get the states and electorate onside, but it's coming.
The interest will be the amount of 'give and take' from the states, ACOSS and other parties with self interest.
My tax saving tip is to avoid the GST increase by spending less and you should do as I say, not as I do.