What i propose is BIS(Brisbane Institute of Sport) the aim of it would be similiar to the AIS basically, though be a lot more involved with professional teams.
Brisbane has the Lions, Broncos, Roar, Reds, Bullers and Bulls who are all professional teams and the only teams from each sporting code based in the city, which is the main reason i think this could work, as opposed to Sydney or Melborne.
The idea would be that, rather then each individual team funding there own playing grounds, doctors, training facilities, fitness gurus etc why not combine all teams to train at one massive super facility, much like the AIS.
Though not all sports are directly similiar, they all share simliarities, one of the largest costs and pressing matters these days is medical and psychological issues, which with combined revenue could be much easier to look after.
What im thinking about capital wise is 2 ovals and 2 retangular fields, sand trap, a massive weights room, a hall the size of two baskeball courts, a swimming pool/rehab pool. a medical centre and more advanced testing equipment.
Staff wise is where some of the real benefits could be seen, have specialised doctors would be a realistic option, dieticians, physios, psychologist(culture/welfare support).
It would be a bit congested around March when the Reds, Lions and Broncos are all in season, though it could be overcome.
At the moment, the Reds have Ballymore, Broncos have Red Hill, Lions have Gabba?, Roar are based at Richmond, Cricket has Gabba? and the bullets train in my backyard.
It would seem to save money and further enchance the professionalism of each team to join all the facilities.