We ALREADY have a chart that is more restrictive than the GCC. It is called the limited chart.
Go here and scroll to the 4th page:
The chart proposed here is intended to replace the limited chart.
At the competition committee in K.C. this was addressed. Meck mentioned that he sometimes overcalls with a void, because it is the right bridge action and it is natural.
It was agreed that the definitions section would drop the "overcall" portion of the definition.