Screamscape sources have confirmed for us that the Guardians of the Galaxy transformation for the Twilight Zone: Tower of Terror attraction at Disney California Adventure is 100% locked in now and happening. While we don't know exactly when the ride will close down (best guess is sometime after summer, either in fall or early winter) the plan is to have the new Guardians version up and running in time for the May 2017 opening of the Guardians of the Galaxy 2 movie premier.
As we previously rumored, the overall theme of the building will now be based around the character from the first film known as The Collector, or more importantly, his collection of rare and unique artifacts gathered from around the galaxy. I've been told that the story will essentially be somewhat similar to the unique story told in Tokyo DisneySea's Tower of Terror...but with a Marvel/SciFi spin to it all. As we saw in the first Guardian's film, sometimes the items gathered by The Collector can be a bit temperamental, and even explosive.
This will be the starting block for what will eventually become a Marvel themed section of the park it seems, but the main problem is that the transition from the old "Hollywood" theme into the new SciFi theme is going to be quite jarring and sudden, to say the least. So it should be interesting to see how this plays out as the first Marvel themed attraction for the US market.