I think there are alot of SG's that could put themselves in the running for spots at next years Olympics:
James Harvey: Averaged 14.8ppg and still is a nice shooter even with the injuries last season (Was quite shocked to see that he is 32, thought he was 35 or so). If he goes out and gets 20ppg next season, surely he could put himself in contention. Nice size at 6"5.5, would just have to develop defence.
Peter Crawford: One of the front-runners at this stage, having played for the Boomers alot recently.
Very nice shooter once again..Probably not as consistent as you would want your SG to be though.
Ben Madgen: Deceptively 6"4. Nice shooter, Had some big games last year (19 vs, NZL, 22 vs. MEL, 25 vs. ADL, 19 vs. WLG, 17 vs. WLG, 17 vs. MEL). If he comes out and puts up some numbers, he could be in contention. I think he is more of a SG than what Martin or Delly or Gibbo are.
Chris Goulding: Very nice shooter, both catch and shoot and off the dribble. May need to develop defense though and work on conditioning. 6"4 SG who is a natural SG because he is always looking for his shot. Avg. 12ppg last year.
Nathan Herbert: Very very good defensive player. If he could put up big numbers for the 36ers, he could be in contention (IMHO, I can see him giving just as much as Crawford at both ends of the floor)
Some of those names you might think shouldn't even be in contention for Boomers spots, but at the end of the day, there aren't too many quality SG's (2 man) out there. Newley and Ingles are SF (3 spot) and Barlow is 3/4 man. They don't have the foot speed to contain SG's at International Level.
I think anyone of those SG'a above ^^ could be in contention if they have good NBL Seasons.
Crawford only averaged 13 ppg last season, hence he isn't exactly as offensively potent as Harvey. He is same age as Harvey too.
I think his defense is more developed than someone like Harvey, but if Harvey can get his defense right theres no reason why he shouldn't be in the squad at least.