Rebates and fees are changing from 1st July, making most new car purchasers at least $1500 worse off, and removing much of the rebate from hybrids (PHEVs will still get something but most other hybrids miss out). 

Do people think they will buy now to avoid the price changes?

The only category that will be better off is used EVs, by $57, but all other categories lose out. Only cars below with CO2 emissions below 100 g/km will now get a rebate, so a used Prius S that currently gets a $1,429 rebate will soon get no rebate at all.

More details are here and it is only for a very tiny range around 150 g/km where the difference for new cars is less than $1500 (look at vertical distance between the two lines on the graphs). For used cars the biggest impact is on hybrids and smaller petrol and diesel cars.