I would suggest looking into a check in call service. These services either call you or have you call them at a regular interval to make sure you are okay. If the regular contact is not made, they can alert family, friends, or emergency services.
I would set it so that they contact a friend or family member who knows that you have a cat who will need to be cared for.
You can find these services by googling "senior check in call", or asking your local hospital or community/senior services center. This type of service can not only help your cat, but if you become incapacitated and cannot call for help it will ensure you receive help!
Finally, you should make long term arrangements for the care of your cat. You can ask a friend or family member to take your cat after you have passed, but if they aren't immediately eager your cat may be better off with a no-kill shelter that you leave some money with. You should consult with a lawyer to set these arrangements up in your will.