The situation (a broken system that cannot be upgraded)  could be mitigated a little bit by using yum + system snapshots. You can rollback to a previous sane system.

There is a plugin yum-plugin-fs-snapshot, but it requires better documentation and system integration.

Currently (I don't know how current is F16 documentation) it requires running lvm by hand

http://docs.fedoraproject.org/en-US/Fedora/16/html/System_Administrators_Guide/sec-Plugin_Descriptions.html

Sergio