The traditional way for companies to learn this lesson are all gone (antitrust breakups, or Innovator's Dilemma-style disruption) since M&A is at an all-time high, antitrust isn't enforced, and companies can just acquire innovative startups.

I'm not even convinced that antitrust would fix it at this point. Someone might need to invent "therapy but for corporations" so big orgs can rid themselves of dysfunction (as if).