Although Microsoft confirmed back in September that TMG 2010 is the last version of the product, it appears that it might still get at least one more update, along with its not-yet-dead cousin, UAG. Word is that updates for TMG and UAG, designed to help them work with Exchange 2013, are going to be forthcoming, although there is no information yet on when these updates might be released. For more information, see Kurt Mackie’s article over on the Redmond Magazine web site:
http://redmondmag.com/articles/2012/11/26/microsoft-planning-tmg-and-uag-updates.aspx