The goal of the ARU should be to make rugby Australia's national sport. This is done by boosting popularity, which is done by winning more, specifically become the best in the World. In order to achieve this, as many have pointed out, it is essential to develop another tier of rugby in Australia.
In this regard, the best thing for Rugby in Australia would be the re-establishment of the ARC. However, due to various reasons, that is not a realistic option in the short/medium-term. Instead, I think there should be a formal 2nd XV competition. A competition amongst the Australian Super rugby sides with their 'A' teams. For example, NSW A plays QLD A prior to the 1st XV clashes. Each team plays each other once, for example NSW A plays QLD A once a year, alternating between Sydney and Brisbane.
The benefits it would provide to player's development is enormous and obvious.
The main issue, as with most ideas, is cost. Who pays for it? Well hopefully itself! Rugby fixtures have very high fixed costs and it makes sense to play more rugby on those nights/afternoons when these costs are already sunk. Revenue will significantly increase as families are more encouraged to go, 'two games for the price of one' (marketing). The event will start earlier, and go for longer. People will be more likely to buy food and drinks at the game. Hopefully, this pays for the costs of travel, sleeping, and perhaps coaching staff. If not, ARU, State Unions and even players themselves have a significant incentive to bear the costs. The costs will not be huge at all, with each team only playing two or three away games annually.
Two options for coaching: firstly, nominate a coach from each local competition to coach each team for the year. For example, John Manenti could coach NSW A. There is an incentive for John to do this, however, it could present complications on clashes between NSW A and Eastwood. The second option would be to have a member of each Super team's coaching staff be the head coach of NSW A. For example, Scott Bowen could be the head coach of NSW A. This would improve overall management team of each Super team and allow future coaches to be groomed.
In summary, this is a fairly quick option. It could commence in 2012, with a one-off game between NSW A and QLD A. Then into a formal competition in 2012, with all five States. It is the fastest, easiest and most cheapest way of introducing another tier to Australian rugby. From 2012, should it prove a success, increase the annual matches to eight each (from four). I think this system will provide significant on-field success to the Super sides and thus the Wallabies. Boosting popularity and therefore making a re-establishment of the ARC a realistic goal in the next few years.