While I, and others, have been pushing for this for about 30 years, I am loathe to get involved. Why, because if it is to be done then it needs the same rules, same procedures and same pilot habits that make the US Class E work.
We have already been told the base will be 1500 Feet AGL, why? The purpose of Class E in the US is to safeguard the flight of IFR aircraft, particularly in IMC. The base is therefore generally 1200 AGL where an IFR aircraft should be visual, 700 feet AGL associated with an airfield approach, and ground level where there is an approach minimum below 700 feet. And if that makes your mind boggle, I have seen it, it works! Originally the Class E (Originally VFR exempt airspace) was contained within corridors called Federal Airways, leading from the Class A (Originally PCA or Positive Control Airspace) down to particular airfields, we have a bastardised version from Melbourne to Ballarat. It only became more widespread with the proliferation of airfields that could support IFR operations and with the surveillance that had to follow to ensure safety. Surveillance was never a prerequisite for Class E, and neither was transponder fitment. If you have ever wondered, that is why they have transponder veils around their busiest hubs. to ensure transponder fitment where it is essential to safety. (And yes a VFR pilot can get a special clearence through a transponder veil if required)
I am sure that CASA OAR and Airservices understand all of this, so a I am predicting a dog's breakfast that will eventually be knocked back by industry because it is so restrictive. The result will be what we have now, which I suspect the DIRD establishment (or Deep State) is really after.