If Gremmy really is the strongest next to ywach and hashwalt then the quincy are done for, Ichigo>>>kenpachi>>gremmy>the rest of the sternritters.
There is only some letters left, so either the spirit king and/or some of the royal guards must be an enemy because what else is there after they beat ywach? maybe ywach has good intentions but is doing it in an evil way.