Point of the matter is that fishkeeping and associated laws in Australia have been arse backwards for a long time. One just has to look at the current noxious list and realise that a large portion of the banned species pose less of a risk to our waterways than many commonly kept fish(especially american cichlids), many of which are fairly aggressive piscivores, territorial, more prolific breeders and probably able to tolerate and establish over a greater range than the noxious species. The current noxious list is mostly public hype(piranha, wolves, maybe some snakeheads etc). These fish were never likely to take over our rivers except maybe the far north where any fish species poses as much of a risk.
As for the whole dumping "problem", gimme a break. No-one is gonna be dumping a fish worth hundreds of dollars when they tire of it or it gets to big. Our exotics market is quite capable of re-homing any unwanted tankbusters. One just has to check the classifieds on any aus forum to realise this. Also I'm yet to hear about established populations of exotics and tankbusters. All the problem feral fish(tilapia excluded) are bread and butter fish, goldfish, koi, guppies, swordtails, maybe the odd population of convicts. Now these are gonna be the only fish you may be able to keep? Again, arse backwards.
I don't see this proposal going through in it's entirety. I'm sure some things are going on the noxious list(bichirs, cichla, aros are my bets) but the industry is going to go mental if they pull a blanket ban. Regardless, many serious collectors already have specimens of dubious origin as far as our allowable imports list is concerned and any changes to our lists is unlikely to affect that side of the hobby.