Activision has your back. If you buy the game's PS3 version, you'll be able to upgrade to the PS4 version as soon as it releases 10 days later, at a price of $US10.
In the US, Amazon and Gamestop will be running a similar limited-time deal for the game's Xbox 360 and Xbox One versions. In both console families, these upgrades will also allow you to bring over all "Season Pass Content and (...) in-game progress." Generous!
UPDATE: Activision has just informed us that this deal is also available in Australia, the price to upgrade here is $10 Australian.