The browser vendors are the primary distribution hubs for Add-on's. Getting on the recomended list can be the difference between 100 or 1,000's of daily downloads. The current hubs provide no real method to facilitate a transaction and last year's Add-on-Con uncovered that most add-ons are trying to monitize using the same techniques as websites.
The opportunity to sell software directly to the end consumer is currently not an option. Even though add-on vendors have to deal with the same issues as packaged software vendors, such as downloads, instalation and support.
The opening keynote will explore the benfits, to the add-on community, of converting the current distribution hubs into payment systems.