It looks as if Kotter may have been optimistic.
McKinsey has found that only a third of transformations of any kind (eg completing a merger, dealing with a crisis, or reducing costs) are deemed very or extremely successful.
"At companies that did change successfully, transformations were managed differently. Among the differences: they were likelier to have set clear, high goals; to use large number of tactics to engage employees; and to communicate about the change positively, not just by pointing out problems."
So fairly similar advice to Kotter. I still think there's more...