What are the chances that if the individuals could muster the same legal firepower that the bank has that the case against them would also fall apart?

The relevant sentence in the article is:

"Facing indictment and the threat of long prison sentences, eight Abacus loan department employees entered guilty pleas and agreed to cooperate with the district attorney’s investigation."

So according to the article it was the threat of long prison sentences that caused them to enter guilty pleas, not that they were in any way found guilty after a trial.

In short: there was no trial, so whether or not the case against them would fall apart if there had been remains to be seen.

But the article strongly suggests that the main culprit set up underlings to defer to his higher authority. That makes them a lot less culpable than the indictment would make you believe.