New Queue?: Locked Queue
Probably a stupid idea, but what if there was a Queue where you pick only 1 role, and you are locked into that role for the entire season. Meaning if you select mid, you can only play Mid in this specific queue (you can still play traditional solo queue).
The purpose would be for players to flesh out their favorite role and become better at the game in this specific area, like how actual pro players operate. Each person on a LCS team play only 1 role, but in our current ranked system, you are forced to play 2-3 roles under the pretext of faster queue times.
The way I would implement this into the game is to combine matchmaking for locked queue and solo queue. You would get 2 options: you could opt to queue for strictly locked queue, and agree to the longer queue times. Or you could queue for Locked Queue and Solo Queue at the same time, and the system would prioritize your first choice, and place you into a locked queue game, but if your particular role is not needed in the matchmaking system (too many people are queued for your role), it would open up your second option and place you into a solo queue game where your second option is needed, and possibly a 3rd option if this new method slows down queue times.
Being locked into a Primary role for an entire season would certainly be a big commitment on the player's part to take on, but keep in mind, if you aren't feeling like playing your primary role on a certain day, you can always have fun in draft pick playing the other roles. There is a benefit to this system that when you are playing your primary role, you know the other 4 people are playing their's as well. They took the same commitment as you, so you no longer have to wonder (is this person playing x champion in x role for the first time in my ranked promos?). And overall should create a better ranked experience in my opinion. But I could be wrong.