Keep in mind, this is not a sudden change practically. Not even the
Lucasfilm Story Group is sure on how to play things out in the future. Essentially, the continuity of what was the Expanded Universe will be gone. With the new movies coming out, the history of post-ROTJ Expanded Universe will naturally be wiped out. Yet, a lot of the things and planets and species from the Expanded Universe will be adapted into the new, singular Canon.
Bottom line: Legends is not simply disappearing. This move is to allow for new licensed Star Wars material to go forward in creating new material without having to worry about meticulously following a conflicting and disjointed Expanded Universe. Legends is now a resource to pull ideas from for future Star Wars material - but not a part of the continuity itself.
An example of this would be Yuuzhan Vong and Thrawn appearing in the new trilogy yet the events of Heir to the Empire and New Jedi Order never happened according to the movies.
With Star Wars RP Chaos being set in a time after a massive dark age, this works well for us. Characters would logically not know much about the history of the galaxy before the Gulag Plague, yet a lot of the planets and species from the Expanded Universe are still out there for us to use.
We will know more about how Lucasfilm will be treating the new Canon when the upcoming novels come out. We will also know in the upcoming months for sure whether or not everything in the Expanded Universe will be branded under Legends - Lucasfilm officials at the moment are erring on the side of caution and telling people to assume everything will be Legends.
Understand, too, that this decision and many of Lucasflim's decisions aren't directly caused by Disney. I find it hard to believe that Disney's executive board cares about what is and isn't canon. Their goal is to make money off of licensed Star Wars works and merchandise. Kathleen Kennedy, the President of Lucasfilm, probably doesn't even care. This is a decision brought forth by the Lucasfilm Story Group and those a part of the group - one of whom was always a strong supporter of the idea that the films and TCW are the only ironclad Canon and that Expanded Universe is simply a resource for them.