Hopefully it won't come to that - one Terri Schiavo is more than enough. I'm not sure what form any changes would take, because, realistically, the laws on guardianship and end-of-life issues work pretty well and are pretty much the way most people want them. There are no easy solutions that I see, but I don't claim to see everything possible either.
Fixing pesky loopholes in the law is like plugging leaks in a dike. One pops up every time you turn around.