So a Big Four is set to fail?.

Thank goodness I'm not the only one concerned about this. As Dennis Howlett notes:

As ... I have been warning for well over two years now, one if not all of the Big Four will collapse. No amount of posturing by regulatory bodies will prevent aggrieved stakeholders from pursuing legal remedies in light of some of the more egregious cases such as Satyam or what’s fallen out of the banking crisis. It is the weight of litigation that will trigger a collapse. Satyam alone could do that in regard to PWC. The question comes — what next? That’s where FRC and others’ focus should be placed.

Precisely.

But there's no evidence it's happening.