Turboshafts
A redesign as you suggest with a stiff casing could, to describe it in a term you will understand better than most, result in a 'schlimmbesserung'. Not only would the stiffness increase be counter to load sharing among planet gears but by containing fragments in a space designed only for gears' running clearances you could jam up the gearbox with equally catastrophic consequences.
You are getting there, recognising the need to secure the bottom of the mast after epicyclic failure, but there are more practical ways of achieving this than an array of up to 10 suspension bars.
I can think of 2 practical solutions, one of which is particularly elegant. It would not surprise me if AH are already working on one, or even both.
It is probably too late for the offshore market but it can be made safe again. Probably in a similar timescale to the bevel gear shaft redesign and replacement.