"Detox" was initially supposed to be literal, "Kingdom Come" was the blueprint for where they wanted to go with Detox. Mature subject matter like "Beach Chair", "Lost Ones", "Minority Report" and "30's The New 20". There's a reason Dre executive produced that album. The album didn't fare well critically so Dre deaded that idea.
Recently he's been saying on the cover, it will have Detox on the front crossed out, making the statement that he's not going to change or "mature", but to most the music isn't believable.
In my opinion Nas got this "mature" hip hop right with "Life Is Good". I don't see Detox coming out anytime in the future, especially with the multi-millions Dre is making with Beats, but with Slim The Mobster out of the studio, and Kendrick in, I think we have a chance of getting higher quality material from here on out if anything did leak.