A bit more exciting probably since the market is higher now which means that the oscillation will be more impressive.

The rest is chicken little - we got into that mess before because neither CDOs nor CDSs were liquid which means that as long as they were not trading banks were able to continue book them at the nominal value and since to trade them one needed to have banks that were on a hook for them to do the trade nothing was moving. That's the biggest issue with those kinds of instruments.

Nothing of sort could happen with the index funds because both the derivatives and the underlying are sufficiently liquid, so the drop won't be 100->20 but rather 100->99.9->99.8->99.7->....->20.1->20 which in turn would re-balance everything.