It's horrible. I don't even see the point. IPv4 and an IPv6 can cohabit. Why would they even alter your IPv4 access?
Australia has a decent number of allocated addresses, around 2 per capita (compare with India, with 29 addresses per 1000 persons)[1], but presumably they will have to be reclaimed from existing users.
A newly started ISP in Australia could get a maximum of 2048 IPv4 addresses from APNIC. [2] If it needed more it would have to transfer them from another owner.
[1] http://en.wikipedia.org/wiki/List_of_countries_by_IPv4_addre...
[2] http://www.apnic.net/community/ipv4-exhaustion/ipv4-exhausti...