Earlier quoted context omitted.
It seems naive and narrow minded to think another company won't step in if there is a continued need for the services that AIG provide{d|s}. But it's unrealistic to think that the vacuum could be filled fast enough to prevent a wave of failures among AIG's clients (banks who bought credit insurance to get around regulatory limits). There's more detail here: http://www.bbc.co.uk/blogs/thereporters/robertpeston/2008/09…
So is this a reasonable system for insuring against the collapse of insurers (and the world's financial infrastructure)? Government rescues? How about limiting the size of companies that are not allowed to die for damage control? Or limiting their ability to become companies not allowed to die?
This article sums up the dilemma Treasury faces, including the whole "too big to fail" problem: http://dealbook.blogs.nytimes.com/2008/09/17/henry-paulsons-...