I'd be surprised if Rudan was keen. With Ange leaving the Socceroos in mid 2018, Arnie would be favourite to take over, leaving a vacant Sydney post. Reckon he'd have his eyes on that.
Rudan might be a long shot for Sydney simply because there is too much money riding on their performance in ACL next season. I would not be surprised if we see him turning up at Jets or CCM first, if not here, to get the hang of it.