I've been actively avoiding tragedy from elderly drivers for 35 years and it's only going to get worse with the aging of the baby boomers. Why fight it?
Instead, we should embrace our American flare for independence and create a form of bumper/smart car and then designate or create lanes specifically for elderly, beginning, or otherwise impaired, drivers' use, should they choose. It would take years, but we do it for bicycles!
We need to stop trying to control other people from our fear, and figure out how to deal with reality.