I would suggest returning to a stand alone personal firewall, these integrated firewalls that Norton and McAfee are producing now have very few features and lack end user configurability that older Norton firewalls had. Using NPF 2003 as the model I would retain the alert tracker which was dropped for 2004, add the network tracer which appeared in 2005 and was dropped for 2006, make a number of enhancements to the way firewall rules are created and work as well as a number of other minor tweaks to the program. The new firewall could be marketed as a Professional version that requires at least some understanding of networking, or at least the patience to learn it. Barring the willingness of Norton/Symantec to build such a firewall they should at least build their newer stand alone anti-virus programs to be compatible with the older personal firewalls.
I would be happy to lead a team to build this firewall and provide the direction necessary to get it built properly and see that the marketing of it is a sucess.