I think we're more apt to see Semih. If Shaq's already having problems with his sore hips, he's going to be sitting out a few games and shouldn't be playing much more than 20MPG anyway. JO will obviously pick up most of the slack, but there will be games when Shaq's not available and they'd rather have the seven footer in there instead of having BBD play out of position.
Not saying he'll be a *rotation* player, but Semih looks like he couple handle a few 10 or 15 minute stints on nights when Shaq needs to rest.
As to Baby Heinsohn, I really don't see him playing a lot of the SF, he really looks more like a stretch 4 to me, which means playing behind KG, BBD, and in some cases behind JO. I can see him spending time in Maine just to stay sharp and work on his game, but I see him as being less likely to be on the 12-man active roster.