I think you will find that the SANFL commission would be vehemently against it.
No way would anyone in the SANFL believe that sending Adelaide and Port to the VFL and thus introducing a third brand of football to SA which would compete directly with the SANFL for patrons, advertising, sponsorship and players would be a win/win scenario.
I don't think advertising and sponsorship is a major part, most sponsors of SANFL clubs and I say most do it not because of the financial return but because of their involvement or love of the club. As for Patrons it's dropping now quite substantially over the last 3 years since introduction of course you would lose those that went to port and crows supporters that's a given. But will it halt the reduction in traditional supporters who aren't going?
As for the SANFL commission I don't think they are keeping them in for any other reason than their working relationship with the AFL, it's pretty damn clear if the clubs polled their members they would be kicked out. But more politics are and have been at play here which is why they remain. This reason alone is probably a fair one as both the AFL and SANFL are trying to do what they think is best for footy. As the AFL holds the purse strings the SANFL are somewhat restricted. It's probably not what the supporters or fans of the SANFL competition want but that's not the issue it's political which sounds weird