Sinclair has indeed popped up as an assistant at SKOBs, Tanner has retired due to age/injuries/work/family, Gatehouse is continuing and not an "old bloke". Not a lot of recruiting happening at SMS, the average age is still under 25 and improvement is expected to come from their young guys getting bigger, stronger, faster.
VAFA Clearance page suggests otherwise. Gatehouse off to the Mid Gippsland league.
SMS have however picked up Joel Mattiske from De La. Only managed a handful of senior games over several seasons but expect he will do very well at this level.