Questions include whether a state Government will back the fight, with South Australia trumpeting the economic benefits of supporting the Anthony Mundine-Danny Green contest.
Paul Gallen - footballers don't come any tougher. Photo / Photosport
Gallen, the mighty forward who led the Cronulla Sharks to their first title last season, is retiring at the end of 2017.
Williams is contracted to the All Blacks until the 2019 World Cup and has a clause allowing him to box in the off-season.
SBW made his professional debut in 2009 and is undefeated in seven fights. Gallen has a similar record, which includes a win over Warriors forward Bodene Thompson, and charity-bout wins over All Blacks Hika Elliot and Liam Messam.