Financially? Sure. Politically? Not a chance, they'll get bailed out or partially nationalized.

Frontier labs will be considered essential to national security, Microsoft is basically a public utility at this point, Facebook is too important for the spread of propaganda (although this one has less of a case/justification for a government bailout), Amazon (via AWS) runs massive parts of the federal gov (along with Azure), Google dying would cause almost an immediate global depression (73% of mobiles run android, the massive ad network).

These companies are so entrenched in day to day operations and into the economy that they cannot fail without ushering in whats effectively dark ages 2.0

After the bailouts of 2008, I think the only thing to fear is that the US government will fail first. As long as they can afford to keep big businesses going, they will. Whether things will get bad enough that the government can't afford to do that is an exercise to the reader.

I don't think the big companies will fail, but their stock prices could dramatically drop. I think newer smaller companies like OpenAI and Anthropic could easily fail, as well as a bunch of other AI start ups. Altogether it could make for some difficult financial times like in 2000 and 2008

What do we mean by big companies? Because SpaceX is giant and can for sure fail. But do you mean companies with an actual, reliable business model?

Yahoo failed. AOL failed.