Quick play is a big failure of the devs in my opinion. I already expected this when they announced the feature. Quick play is just the same as ranked, but with some different game modes and without balanced games. That last part is just killing quick play. Games are always unbalanced, so it is not fun to play. You are better off with joining ranked for RM. If you want to play EW or BR, then it is easier to just go to the lobby and make your own balanced teams. Quick play was meant to be the quickest way to get into a game, but it turned out to be the slowest way to get into a game.
The best solution (in my opinion) is therefore to just delete quick play from the game and add EW to the ranked queue. I do think there is a player base for this game mode, based on the Redbull tournaments. Also the devs seems to want to push this game mode as well by placing it into quick play.
Maybe we can also add BR to ranked, but i feel like there isnt really a large enough player base who want to play BR. The main reason to still add BR to ranked is because the devs like to push there new game mode.
In ranked you can already sign up for all different game modes at the same times. Currently it is already possible to sign up for RM and DM in ranked. So your solution is already part of the game for ranked.
Less different modes to play MP (Ranked, quick play, lobby) also means less division of the player base over different queues. So deleting QP will also have this benefit to the game as weel.
In the end i dont think your idea is a good reason to add lots of additional game types. A queue only works if the player base is sufficient enough. For a small niche game mode a queue would never work. Such games can still be played in the lobby.