Another Carter is exactly what this team could use. This is a playoff trade, start there.
Forget the notion that we keep needing young fast skaters - think ahead to when the games slow down, our small fast guys are interfered with and can do nothing about it (because of their skill and size), whistles are put away and our offense gets stymied because teams take advantage knowing they won't be called for it. There's nothing that more 5'5" guys with blazing speed can bring to this team. Shoring up inconsistency in the bottom 6 and a solid defensive depth piece is what we could use, if anything.
Carter is an ace on this team, slotting up and down - knows where goals are scored - and has the frame, proven, to be successful in tight playoff games. Adding a 6' LW (or C) who can play with Geno, or play with Carter (or both) - or hold his own in a bottom 6 role - who knows where goals are scored and has the experience that helps so much in the playoffs would be ideal. Then you can factor he's not on the hook for next season and would love to possibly go out on top.
This isn't something I'd necessarily champion starting a fresh year in Sully's system (perhaps if we adopted a different style though), this is a move that could benefit the Penguins style for the rest of the season.