Separated post to actually answer the OP's question:

It is very likely that your Centurion card covers Trip Cancellation, Delay, Interruption, as well as Accidental Death and Dismemberment. Also likely it will cover Baggage, but that's not a certainty. Travel medical insurance may be part of your employment benefits. However, its coverage may not be enough in the event of a serious accident, such as getting hit by a car. For some reason, coverage of $10k USD seems to be the "normal" level when you purchase travel medical insurance at, say, worldnomads.com. Depending on where you're travelling, this could be grossly insufficient.

From a separate thread, it appears that most US credit cards (even Amex Platinum, for example) do not cover travel medical insurance.