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.
What I’m doing: My realistic goal is to have a blended annual return of 2x the risk free rate. With a current 5% hurdle, I am not paying down mortgages that cost less than 4%. Debt at 5% is a wash. My realistic blue sky scenario is a 3-4X rate of return over the risk free rate which can be achieved with property, stocks so far for the past five years, and certain private equity investments. Where I am dragging is my blended average CD interest rate of roughly 3% from an old CD coming due. I’ve rolled some money into a 12-month CD with CIT Bank at 2.5%. It’s the best rate I can find. 
One thing I’ve realized is this: It’s FAR easier to work for an employer than it is to develop durable passive income streams for the average person. Why? Because working for an employer in a place that “needs” you means that it’s possible to show up and give a 50% effort. You can show up, put in your time, go home, have a beer, watch TV, and rinse and repeat all without REALLY having to put in the effort.
Online business owners looking for multiple streams of income and residual income might consider publishing an e-book. Software to create an e-book makes the process simple. Even online business owners with no previous writing experience can write an e-book that will help readers find their online business website and provide opportunities for residual income.
7. Royalties: the creation of music, books, inventions, machines, patents. A royalty is something you have sold or created and put it on a platform that you do not run and then receive compensation based on when the item is purchased or used. Most of us do not have the potential to quickly create royalty streams. Not to say you couldn’t specialize in something and write an ebook or if you are musically inclined you couldn’t write a song, but to create true residual income, that is going to take a lot of effort and skill. This is the purest form of passive residual income, if you can achieve it.
What I did: I first identified my favorite places in the world to live: San Francisco, Honolulu, Paris, Amsterdam, New York City, and Lake Tahoe. I then looked up the median rent and housing prices for each city. Then I factored in private education costs for two kids to be conservative given I may not have two kids and public schools are often good enough. After calculating all vital costs, I then did a self-assessment of how happy I was making $50,000, $100,000, $150,000, $200,000, $250,000, $350,000, $500,000, and $750,000. I decided working 20 hours a week making $200,000 a year is the best income balance for maximum happiness. 
Real estate is the obvious choice if you are going to make money on your money. I personally am not at the point where I can do any of this in a meaningful way BUT my parents are and they now own a couple homes outright and are collecting income from them to power their retirement income. It makes a lot more sense for anyone that has a chunk of cash sitting in the bank and are planning on slowly drawing from it because you technically still have all that money in a property (or multiple properties) and can sell them if you really need the lump sum of cash but you’ll earn great interest payments until you do that.