If the majority of players which move on to open queue are dps, it will be a glorified quickplay+ mode.
Having no tanks was already bad when it was the only comp mode, but now having any hope for a functional comp if thats the case will be pointless.
If its an even split of roles, then queue times will go through the roof and everyone has to wait longer for a game. Either way, i think it can only hurt the game.
If that happens might was well play quickplay, lol.