The Thunderbird Council is optimistic about the future. With the organizational question settled, we can focus on the technical challenges ahead. Thunderbird will remain a Gecko-based application at least in the midterm, but many of the technologies Thunderbird relies upon in that platform will one day no longer be supported. The long term plan is to migrate our code to web technologies
Mozilla dumps XUL tech from gecko left and right, removed proper "classic" mod support from Firefox... how is this a bright future. Thunderbird as a big XUL app is stuck with an soon to be not supported old gecko. And how is the plan to slowly rewrite it viable? Replication of the dated UI with HTML5 will be an even bigger clusterfxxk.
We need a proper open source offline client. And it should have a modern UI with at least conversation view like Gmail. Wasn't there a HTML5 based email client in FirefoxOS. Start with that code and set up a new Mozilla foundation funded offline email client, and keep security support for Thunderbird until the new email app is ready.