Owen Daniels has had three torn ACLs in his career. He took a while to come back after the most recent one, but he did recover.
Adrian Peterson tore both an ACL and MCL on Dec. 24, 2011, and he's back to playing now. They say it's almost inhuman for someone to recover from that as quickly as he has though.
Jamaal Charles tore his ACL last year in week 2 and he's back to what appears to be 100%.
Rashad Mendenhall tore his ACL last year just before the playoffs. He didn't start playing much until week 5 of this season, but he looked good in his first game.
Terrell Suggs tore his in May, but expects to be playing for the Ravens in November. Only a 6 month recovery, which is aggressive.
I don't think we need to worry about Cushing coming back next year, he will have 9-10 months before meaningful practices start. He's a warrior, and I'm sure he will train extremely hard and make himself ready to return ASAP. It just won't happen until next year