My concerns about the next season's ranked system
We will have a separate rank for every role.
Will we also have a separate rank for every queue? (e.g. soloQ midlane rank, flexQ midlane rank, ...)
If no, then we are back in the season 6. Simply use your friends in flexQ to boost your role-specific rank, and then play in soloQ on elo where you don't belong to.
Will duoQ be still part of currently named "solo/duo queue"?
If yes, then there is a very similar problem of boosting. Example: A friend plays all roles as platinum. But after the placements, his all roles are in low gold. I will keep playing just one role, while the friend is going to change the role once he reaches platinum with it. Until he reaches platinum with all roles, I'm gonna get my role-rank eloboosted by him.