Doubt it was the NHI that broke their backs.
Their history of an inept, undecided cleptocracy was so overwhelming that even NHI could not turn the tide for them. It really was Zuma that tore them apart. If they only had real balls and not committee mandated prosthetics they should have taken decisive action against the thieves amongst them. Sadly (from their perspective) it would have left just a few standing, so they took no real action. So here they are
They allowed Zuma to dictate the narrative when they treated him as a 'wronged friend' and not the destructive, self interested fraudster he is. Should have come out strongly against him. But then I believe they all looked up at him as 'uBaba'.
PS : I understand the desire and narrative to shoot down the NHI as it is written now. But it was not what sank the ANC. It was the bilge pump that could not keep the sinking, rotten ship afloat