The only way Broncos could ever own a stadium is if it's Lang Park, we would need atleast a 35k seater for it to be worth it since we easily make decent profit playing there at the moment even including the huge rent of around 3 million going by the annual financials(it's about 50% going to us after rent atm).
To build your own stadium in this economy with massively inflated building costs would cost more then it would to buy Lang Park as it is, that's the problem.
I doubt the Government would sell a profitable stadium as well, I think given how much extra revenue we have over what we need to run the squad we can afford the several hundred million dollar loan required to buy it, but we would also require the same amount of tenant's there currently to pay it off.
I think as long as NRL keeps going in the same direction with TV revenue growth we will get to that point at some stage, but we would likely need a rich owner that isn't Newscorp to do it in the next 20 years or so, unless the QLD government somehow approves of it.