Yep, Disney is building a marvel land behind the tower of terror and is re-theming it to better fit in. Pisses me off because the whole theme of California adventure is California. Even the newest developments with the carthaway circle and trolleys. The paradise pier area is laid out to feel like a California board walk with carnival games and a roller coaster (California screamin). For this reason the Hollywood Tower of Terror was the perfect ride to fit that theme. Unfortunately someone high up is greedy and said "well marvel will bring more people to the park and make us more money, so let's move away from the previous theming for this reason." The most visible ride in that park is/was tower of terror because of its height. Now while it will fit into the marvel land behind it, it will also detract from the California feel of the park the second you walk into it.
I love GotG and marvel so I'll survive, but I'm not sure Mr. Disney would be in favor of this change if he were here today.
Also, they aren't changing the ride mechanics. It will be the same ride, just re-themed to GotG.