I'll preface this with "it may not be true" but...I agree the "trans-tasman bubble" has merit - but it seems a little ambitious without freedom of movement within Australia first. It doesn't hurt to plan to open up flights to/from NZ, but in the context of a broader timetable of lifting domestic travel restrictions first.
As for the wider international restrictions, a further statement from the PM regarding the next few months would be helpful. We have bookings for August and September - I expect to cancel them, but for now I am waiting for something that will limit "cancellation fees" such as a continuation of the "do not travel" direction. For now any cancellation would be regarded as "voluntary".
I understand that each of the state jurisdictions are looking at this themselves and, from what I understand, one key requirement as to whether to open up to a particular destination will be the extent of community transmission in that destination. So you could potentially see SA, for example, opening its borders to NZ but not to NSW if there is no community transmission in NZ and still ongoing community transmission in NSW. Not saying that will definitely happen, but it's not a given that freedom of domestic movement is a prerequisite for some international routes to restart.