Once the Highway upgrades have been completed (if) then it should be No. 1, at least by Australian standards, still lacks a lot compared to other countries, especially when a recent study came back and said the Highway was unsafe to raise the speed limit to 120km/h, I think it was.
As for the existing Highway, where it is bypassed it will become just another local road and handed over to Councils to maintain. The Councils get a one of lump sum to go towards the road but that is about it.
I guess you look at it two ways, the new Highway to get from A to B and the old highway to go from A to Z at your leisure without all the Highway traffic.