I agree, I think in the end it will be Grissom vs. Freeny vs. Bolden for a roster spot on the 53 via ST.
This is one of the reasons why I wish I had a better knowledge/understanding of the specific roles that each player has on the various ST units.
In other words for punt team duties (example), I know the two gunners, the long snapper and punter, and I know there's a personal protector, but I'm not sure if that means that all the remaining positions (6) would be wedge blockers or not? Also, if I recall correctly, Bolden has provided duties as the personal protector at times, and that isn't something that a guy like Grissom could necessarily provide, so we'd then have to assume that either Chung (we remember him having that role in his first stint here, mostly due to the fake punt gaffe in the 2010 divisional round loss to the NYJ) or maybe Burkhead could cover.
I know one thing, and that's that Bolden has laid some dudes out on the punt unit, both punting and return units. He's got quite the physical presence. We all remember the game vs SD where he destroyed the SD punter (Scifres, maybe?), not only knocking him out of the game, but I believe for the entire season. In other words, it seems as though he may have specific roles that fit his skill set well.
Knowing more about the specific duties would be helpful in trying to determine what kind of fit each specific ST only player would provide when attempting to make roster projections. You'd think that's something that more beat writers would be covering, but I guess they're just like me in the sense that we only notice when major plays occur. I'm wondering if one of our film rats would shed some light on the topic? As you mentioned, a potential loss of a guy like Slater would change things up in the sense that we'd need a replacement gunner to go along with (presumably) Brandon King.