Mike, I don’t consider the income from FS to be passive, as I’m spending time commenting to you right now. But since 75% of my traffic comes from search, the most traffic I would probably lose is 25% for probably a year. And then my search word rankings would probably slowly fade given frequency of posting new content is one of the search algo variables.
To create residual income, you need to create something that people will continue to buy on a regular basis long after you’ve created it. A house is a prime example of this as people will continue to pay rent for the right to live in the house. A business needs to have products that are sold over and over again rather than trading the business owner’s time for money.
Managerial accounting defines residual income in a corporate setting as the amount of leftover operating profit after all costs of capital used to generate the revenues have been paid. It is also considered the company's net operating income or the amount of profit that exceed its required rate of return. Residual income is normally used to assess the performance of a capital investment, team, department or business unit.