Assuming Benson's suspension sticks and Adam Jones is indeed ready to come of PUP, I can easily see the team sticking with its current group of running backs (Scott, Leonard, Peerman) with Scott and Peerman sharing the 1st and 2nd down carries and Leonard handling 3rd down. Taking Leonard out of that role would do more harm than good.
With the open roster space, I would assume Jones can be activated without having to cut someone. Once Benson is reactivated, it gets a little trickier. If there's an injury in the Seattle game, a move to IR might be possible. If no one is hurt, I think Jeromy Miles ends up with the short straw. Mays can take his ST role on, plus Jennings and Hawkins have been good there too. I might have said Vincent Rey but now with Maualuga hurt that seems unlikely. Besides, I don't think the team has ever carried 11 DBs.
On a side note: what the heck is up with Keith Rivers? Joe Reedy has said late November return or IR are the likely possibilities, but the team hasn't even mentioned his name since training camp it seems. Plus do we even know how we was injured? It was classified as "non-football" which only means it didn't happen under team supervision. I'm guessing it was workout related or the team wouldn't have decided to pay him while on PUP (that was a team choice, not league or CBA rules).