Ask HN: How to build companies that last

I want to build products that live for as long as they are useful, irregardless of the fate of the company that starts them.

Too many products i've loved are dying. Wunderlist, Google Hangouts, Parse, etc.

I want to know what you've done to make your product last for a long time. Is open source the answer? Allowing users to self-host? Structuring your company as a non-profit?

How can people build products that live forever?