I think RIO are very long odds. I would be very surprised if they were on the shortlist of three.
DBCT fits QIC's investment criteria perfectly. I also see a consortium involving Macarthur Coal as a definite possibility.
DBCT is an prime infrastructure asset located in QLD, so I see QIC as being a lead member of a consortium bidding for the asset. Consider, over time the predictable regulated income stream matches increasing superannuant income demands and there is political benefit if income generated in QLD is retained for the benefit of Queenslanders.
Secondly I would guess a consortium of the miners, including BHP and RIO. I do not see either of the big miners (BHP or RIO) seeking outright control of the asset.
Thirdly I would see some of the big offshore pension funds in a consortium with some Australian funds. From the pension fund perspective it is a regulated steady income stream that is an exposure to a base resource near major markets in a politically stable economy.
Cheers