Mozilla Foundation finally published a decent transition plan. The basic jist is this, a while ago they decided to seperate the application suite (IRC client, browser, Email, etc) into different applications — Namely Firefox and Thunderbird. The plan was for a slow transition, what really happened is that everyone immediatly moved to the new projects. I personally switched from Mozilla to Firefox as soon as it was in beta (not 1.0 beta, .1 beta — Or what ever it was). The Mozilla Foundation has finally begun their transition, but if you think back, for the last 6months at least (maybe a year or so) the Mozilla browser suite has been quiet, their homepage only advertises Firefox & Thunderbird — And you dont see any spread mozilla campaigns like you do for firefox.
Oh well, at least all the questions are answered now.