With the approaches described in the High Availability Within a Single Site topics, you should be able to withstand most single and possible multiple component failures without incurring an outage. With the appropriate architectural patterns described in Architectural patterns for high availability , you may be able to schedule downtime with less impact to the corporation's overall availability.
There remains one major contingency you need to consider: What happens if a catastrophic event causes your primary data center to be partially or completely incapacitated? The reasons could range from the commonplace disasters such as fires in the building or natural disasters like floods or earthquakes. It may also be rare events like the Northeast Blackout of 2003, when wide regions covering over eight US states and one Canadian province lost power affecting over 50 million people.