Dr Hawking is not a valid comparison.  He is mentally alert and able to communicate his wishes.  And some personality types may wish for their life to be maintained at all costs but others of us, especially those of us who value privacy, autonomy and independence are horrified by the prospect of total dependence and a slow demise.  I have a detailed advanced directive that is not legal under the current assisted dying legislation and it makes me fearful that if I fall on my head while cycling and end up vegetative there is nothing that can be done to end my life.   What a waste of resources in a wasteful world.