So long as the turbine rotor/stator geometry is designed so that a rotor axial shift creates a clash of airfoils, it's a "fail safe" design. The rotor will never get the chance to accelerate to a dangerous RPM. This is apparently what has happened in the GEnx failures; the low-energy airfoil debris exits through the core nozzle.
However, even this "benign" shrapnel can create a flight hazard - for example, if hydraulic lines are routed within the horizontal stab LE. A thorough FMECA is the answer here.
(FMECA = Failure Modes, Effects, Criticality, Analysis)