I’m not sure in the higher ranks, but in the lower ranks where they struggle to kill Reaper and Roadhog screaming oppressive and unkillable, Junkerqueen will thrive there a lot. Lets not forget Widowmaker in lower ranks do not have the mechanical skills to kill Junkerqueen fast enough.
So I’m honestly not worry about how sustainable Junkerqueen is in OW2. The people in higher ranks has more game sense and coordination, so they will make Junkerqueen work somehow.