There is a thread about team 1432 needing some help, and I don't want to hijack that thread, so I will start a new discussion here.
There have been some good points made about planning and taking steps to protect your team. Here are links to two CD white papers that deal with this topic -
Maintaining Sponsors -
http://www.chiefdelphi.com/media/papers/2380
This presentation talks about ways to create and then maintain a strong sponsor base.
Team Continuity Planning -
http://www.chiefdelphi.com/media/papers/2245
This presentation talks about how to identify challenges and risks to your team, and then take steps to manage or elimate them.
One of the keys to sustainability, for a business, a team, any organization, it to continually evaluate the things that could go wrong and manage the ones that you can. Taking some time to evaluate your team and the circumstances around your organization could help you remain a viable team in the future.