If you're referring to our new Seller Admin interface, we conservatively project that should be done by the end of this year at the latest, and optimistically much sooner if all goes to plan.
However, even before then, we may be able to find undocumented template tags or add new ones, as those are not dependent on the current Admin. What variables were you looking to include in your thank-you email templates? This help page lists the template tags we officially support at present:
http://www.e-junkie.com/ej/help.custom.thankyou-email.htm
