Here's a way to have Dynamic Queue and Solo Queue without killing Dynamic for specific group sizes.
Only allow groups of 2, 3, or 5 players.
This ensures that solo players are not needed to finish matchmaking.
This also prevents the scenarios where four players gang up on one, even if they are rare.
The end result would essentially be like seasons 1, 2, 3, 4, and 5, but with far more people participating in the 'team ranked' with groups of 2, 3, or 5, as opposed to solely 5.
I'd still call that a success, and it alienates the fewest amount of people overall.
Why not this, Riot?