NECA has officially announce that they have secured the rights to create products based on all Valve properties:

"The National Entertainment Collectibles Association, Inc. (NECA) announced today that it has entered into an agreement with Valve Corporation to produce consumer products based on all of Valve’s titles. Merchandise will include action figures, toys, board games, accessories, and apparel for all Valve properties."

While the the range of products will likely depend on initial sales, it is a safe bet to assume that we'll see figures from the Half-Life, Team Fortress, Left 4 Dead, and the Portal series. Given how recent the announcement is, it seems unlikely that we'll see prototypes from NECA at the upcoming San Diego Comic Con, but hopefully we'll hear more about their future plans for the Valve product line.

Source: NECA