I believe that the money would dry up for Subi if the stadium was built but as has been mentioned, the financial downturn plus more important priorities in the state means that the stadium is a few more years away yet.
IMO I think Subi might be able to beat the bottom five sides regularly home and away, but may find it harder in Adelaide against the others (they would have a massive advantage playing at Leederville Oval with the 2.5-3 hour flight each way).
It would be better to leave them in the WAFL and prove their worth under the new Player Points System - 130 points for a 55 player list with some severe penalties for infringements (no recruiting outside their allotted zone for 2 years and a 120 point balance for the first sanction-free year). Methinks that the WAFL may become more even with the removal of the salary cap and a more serious attempt at equalisation.