I think of all the suggestions I've seen thrown around of Telltale's official forums, Star Wars is the most commonly requested. I can't say that's surprising -- Star Wars is an amazing franchise, one that is now more relevant than ever and can fit into any genre and type of game/movie/TV show.
We've only gotten one Star Wars game since EA bought the license from LucasArts in 2013, although Lego The Force Awakens is on the horizon. So Telltale would have to get the rights from EA, a company that is very protective of the franchise but seems willing to lend the license when it makes sense and will be handled well. Which is exactly how Telltale would treat the IP.
I'm not even going to try and pitch the story, setting, or characters for this particular game, because Star Wars is an endless well of possibilities. Maybe it's a Han Solo game, an Anakin Skywalker game, or a Boba Fett game. Heck, maybe it's a Watto game. I have no idea, but I do know that whatever it is, it would sell in the millions.
The best thing about this pitch is that it's the only one that Telltale has actually stated it would love to get its hands on. Telltale CEO Kevin Bruner said in a Reddit question that:
"...coming from LucasArts we have so many people here that love Star Wars and have worked with the license so that would be a great fit and very cool."
Of all the suggestions in this list, this is the one that I truly believe is more a matter of time.