Its a conservative forecast as noted by Josh Frydenburg, and is a forecast that has already been pushed back a few quarters. I believe some analysts were predicting the Govt were going to increase their future price estimate too.
In other words, a) I would think the price forecast is required to be quite conserative because it deals with our national budget (better to under predict and over deliver) and b) there are no strong indications that prices wont stay higher for longer at this stage anyway.
