I don't think I've discovered anything as profound or fundamental to the way I think about business than when I (not so long ago) started trying to build systems instead of products.
Your business is a money making machine. There are many components. Absolutely all of the components are hot swappable. Make each component work until the entire machine does. If one component fails, swap it out with something entirely different if you have to. As long as it keeps the machine working, it doesn't really matter what it looks like.
Become attached only to the machine as a whole, not the individual components it's made of.
That sort of implies that all companies should gradually "become" whatever is the most profitable kind of company, though. If it turns out that, say, spam is the most profitable thing a company can do, then your todo-list app, or even your brick-and-mortar home-and-garden store, would gradually swap out parts (including employees and even founders) until it has become an online spamming service!
Your business is a money making machine. There are many components. Absolutely all of the components are hot swappable. Make each component work until the entire machine does. If one component fails, swap it out with something entirely different if you have to. As long as it keeps the machine working, it doesn't really matter what it looks like.
Become attached only to the machine as a whole, not the individual components it's made of.