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.
Residual income is calculated as net income less a charge for the cost of capital. The charge is known as the equity charge and is calculated as the value of equity capital multiplied by the cost of equity or the required rate of return on equity. Given the opportunity cost of equity, a company can have positive net income but negative residual income.