This is the beauty of the NBN, surely. A single provider of the underlying infrastructure and many, many choices as to your biller/modem provider. In the past with cable you were lucky to have a choice between Telstra and Optus, often it was one or the other.
Now with NBN go wherever you want, whenever you want. Unless of course you sign up for a long term contract in order to get a free/cheap modem and then to be honest that's your choice, nobody made you do it!