This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
The Angry Birds Toons episode "Run Chuck Run" was delayed for so long because Rovio wanted it to concide with the full reveal of Angry Birds Go!
What we've only known and seen about Angry Birds Go! so far amounts to a teaser site. Additionally, FOX8's episode guide for Angry Birds Toons lists the episode "Run Chuck Run" as coming between "Slingshot 101" and "Gardening with Terence" (the latter named "Oh My Garden" in the episode guide), but we got "Thunder Chuck" (listed in the episode guide as "Thunderbolts & Lightning"). Now that "Run Chuck Run" is finally slated to be released on the week of 2013-07-28, Rovio may be ready to properly unveil Angry Birds Go! soon, given that the Toons episode is about racing, and Go! is speculated to be a racing game.