The thread idea is kind of the smae approach i use to fix various broken plastics, but I use either fiberglass or carbon fiber.
Here the blade storage portion of this razor knife got ripped off. I glued it back together, then dremmeled grooves in the plastic across the break with a cut off wheel, then filled it with superglue and then laid carbon fiber atop it and pushed it into the grooves.
Probably stronger than when new.
Did this repair several years ago, still in one piece.
Most recently i repaired a broken fan blade on the 5400 rpm screaming banshee Delta fan. I bridged the break with carbon fiber. Threw out the balance a little bit, but it is holding.