This seems exactly right. People agree lean should expand beyond the factor floor but actually doing so lags that belief. Still there is plenty of work to do both in getting companies to do apply the most obvious lean ideas as well as extending those companies that are already successfully applying lean concepts.
The most substantial success requires building upon the initial efforts. Truly becoming a lean organization is not something that can be done easily or quickly. And it can't happen unless management stays focused and continues to learn about lean concepts.