That's a good reason to use OpenID delegation. As long as you remain in control of your domain name your OpenID can never become invalid, even if the provider you delegate to goes out of business.

https://myvidoop.com/help/what-is-delegation

Of course that's only a good solution for relatively technical people like us. Perhaps someone should create a service that automates this process for the average internet user: pick a domain name and OpenID provider, pay your $10 (per year), and you're done.