Here is further clarification of funding, Government will pay at...

Here is further clarification of funding, Government will pay at least half. We still need to know the landing point they are funding it to before we can speculate about the the possibility of augmenting it to server other purposes (eg Cairns->Sydney).
It wouldnt make sense for them to fund the cable to Cairns only, because much of it likely has to go to Sdyney (because thats where other cables are), and apparently Cairns-Brisbane is relatively expensive.
If they want a cheap option they might consider only going to Sunshine-Coast which has good competition for the route to Sydney. But then, if they are thinking of going all the way to Brisbane, they might just say they may as well go all the way to Sydney.
Either way, it looks like there will be a possibility of augmenting the cable and adding a link to Cairns, it wouldnt be much traffic as not much population so it would have to be pretty cheap, but it would be good for the domestic network as a whole, and for our reputation, other carriers would likely be happy to see it happen as well.

"Australia will deliver and majority fund the project as part of a cable system that will connect both Honiara and Port Moresby to Australia, with a financial co-contribution from both Solomon Islands and Papua New Guinea. It is scheduled for completion by the end of 2019."
https://www.itwire.com/government-t...o-huawei-role-in-solomons-undersea-cable.html