Corporate users would still need their administrators to install the plugin. But Chrome Frame could let change-fearing companies keep their users on IE6 (no retraining users or retesting existing sites), and use the Chrome engine only for sites that opt in to it.
I think part of the problem is MS encouraged people to write a bunch of ie6 specific sites. Thus, since ie doesn't AFAIK do side-by-side installs, the need to stay on ie6 for line of business apps.
