When you feel that you can not manage your SFI business anymore due to old age or sickness, train one of your trusted beneficiaries on how to do the SFI business.
Teach this person how to be the best affiliate like you and ask his commitment that he would continue what you have started.
But I guess the best it for you to start it with yourself.....Begin doing this by building a big team of active affiliates to assure you of the residual income