Hit Boy is still around, still doing stuff. He did some work on Beyonce's Lemonade album. I think he got a co-production credit for "Sorry" , not sure in what capacity. Melo-X from Brooklyn also made the beat.
Always used to read on the Future Producer's forum back in the day some of the stuff Polow was known for doing. There was a rumor he stole someone's harddrive or something. He brought Hit Boy and ChaseNCashe into the game though and both of them have made some bangers. Can't be mad at ghost production though as long as the kids under you are getting paid and credited. Dudes at that level can't be in the studio making beats all day, plus out there chopping it up tryin to land big placements. it's impossible. I had no idea Detail had ghost producers or was more of a team than a solo producer until the main dude allegedly got beat up by drake's body guards