How many people willing to fork out? Its depend on the people actually, if he think he has financial stable and dun mind to pay for it for a peaceful sleep every day, why not?
And not all people will go for unlimited lifetime limit, maybe 600k or 900k will do for them? That will not cost so much for sure.
Well some people buy medical card as a rider with their life policy. Use the cash value accumulated to pay the medical card expenses every year. Medical card rider can be paid monthly, for those who can't fork out high premium at once. Standalone? no.