I would think it is no different to other types of "restricted" or other licenses they are giving out now. More a clearance of anything medical that should preclude them from having a drivers license, rather than screening for an entirely new license category. Some states do this already as a matter of course for mature drivers.
As for the overloading problem, a Piper Tomahawk or C150/152 is going to be obvious, but I would agree that compliance with the rules in a 172/182/Archer/Warrior is going to be a tough one, especially in remote areas. May be that CASA takes a lenient view due to the sparseness of population compared to USA/Europe. That in some ways would be a minor win for common sense.
Looking at the stats for car accidents for all population (and "medical" causes included), how many car accidents are DIRECTLY attributable to an acute medical condition occurring behind the wheel? Quite honestly I can only think of a hand full or so in the last 10 years or so, scale this down to the number of people with pilots licenses and it may well be statistically insignificant. The other thing is an aircraft usually has part to fully duplicated controls (unlike a car) and this, even in the hands of an amateur, should give a better survival prospect. Surely it is time to look realistically about the likelihood and consequences of an incident actually occurring mid air (using the same medical criteria for safety of operation of equipment), that may cause more than "local" damage (ie, immediate occupants of aircraft)? A single pilot alone is always going to die, a pilot with passenger(s) has a chance of survival for all occupants.
I also note that the US is having similar questions regarding the possibility of a "Level 3" medical, similar to our new model.