Branch had very solid play in a well respected defense around the league, he may stay out of a sense of "team", but as far as the business of football goes, it's likely he'd get paid better somewhere else.
Jason Jones Signed a one-year deal last season hoping to prove his worth to the market. I think his injury may have been a setback to the longer contract he was looking for and if nobody offers him a deal, I could see him doing another one year deal to once again, try to prove his value for a longer term deal.
Scruggs is a no brainer. He's still a young up and comer but seems to be progressing well, so he stays unless for some reason he totally regresses or lets himself get out of shape in the offseason or something (I highly doubt it)
As for MacDonald and Howard, I think they are both good depth, but they could both easily be on the bubble depending on what the front office does as far as signings and draft.
Honestly, I think we only go big (starter potential) for one DT, I think they may also look to go big (starter potential) for one DE as well unless they make a move for an OLB who can excel at pass rushing as well.
It's really going to be an interesting off season. We have almost all of our starters locked up going into next season, so we can pick up a lot of excellent depth and a few starters this offseason and move forward into next season with some actual consistency.