Mara jade will never show up. The EU was tossed. They may borrow concepts. The likelihood of using actual names of characters from the EU is very low if non-existent.
And yet... TCW and Rebels (especially) have been full of EU concepts...
The thing about "Legends" status is that it's not "this isn't canon", it's "until we say this isn't true, or put something in canon that contradicts it... then you never know.
It's like Schrodinger's canon...
Really? I had no idea.
It is true, alot of EU characters and concepts became canon because of the TV-Shows. Aurra Sing for example was just an interesting extra in Phantom Menace. Comics gave her some backstory of having force powers, then TCW makes them canon.
The Lasat, which existed in exactly the same way as Zeb is depicted in Rebels, were based on Ralph McQuarries Chewbacca concept art. EU named them Lasat, Rebels ev team wanted to adapt this species,too, but before they did it by themselves, they looked if something preexisted in the EU.
Mind you not everything got adapted that way, but a lot. The most recent example that comes to my mind is the Immobilizer 418 cruiser.
BUT! That doesn't mean that they will adapt everything from the old canon to the new and Thank the force they won't. Some of it was TERRIBLE!
Edited by MOELANDER