Djordje is still young, we'll see what happens with him. As for Marko, I watched his match in Dubai against Golubev, I doubt he will have some great results in the future. However, Novak's brothers is likely to face with a lot of pressure because their brother was the best player in the world, it will not be easy for them.
"You are not special. You are not a beautiful or unique snowflake. You're the same decaying organic matter as everything else." - Durden