So, how does one prepare for the worst? Let’s brainstorm:

0. Register alternative domains in advance with a different registrar.

1. Setup mailing list for all registered users and be prepared to blast them with a new domain.

2. Make mobile apps check both the main and the alternative domains.

3. Make the mobile app notify the user of a new domain name requirement via push notification and the like.

4. Setup the phone system so that it can read the new domain before connecting support.

5. Setup support on a different domain (e.g. zen desk). If zendesk goes down users will know to call us, if the main site goes down they may remember to check zendesk.

6...?