From Yannis Koutroupis/Hoopsworld:
After trying to verify reports that Ricky Rubio will be staying with JKV Joventut HOOPSWOLRD has learned that Rubio will not be playing with the team next year and that he’s still working towards joining the Minnesota Timberwolves.

Rubio’s desire to stay with Joventut is overstated as he is ready to make his NBA debut. However, he’s currently staying open to the idea of returning in order to help decrease the buyout of his contract. Prior to June 30th Rubio’s buyout was 4.75 million Euros ($6.6 million), but now it has jumped up to 5.75 million Euro ($8.08 million)…
Villicamp restated these sentiments even after Rubio’s latest comments about wanting to stay with the team, saying that he feels it’s a strategy to further lower his buyout.

Sources tell HOOPSWORLD that Rubio is looking to get the buyout down to $4 million, which he would sign off on today if it was on the table. For now though progress is being made as the buyout price is coming down, but both sides still remain a ways apart. While Rubio may be threatening to just show up to training camp for Joventut, he really wants to be in the NBA and if they can get the buyout amount close to the $4 million mark that’s where he will be.

Links and translations below via HoopsHype.
From Marca:
Ricky Rubio: “They have already told me that (Joventut) has rejected Barça’s offer, so I spoke with my father for him to tell Joventut that I’m staying. I’ve never had a problem with staying at DKV Joventut, which has been my team all my life.”
From As:
Jordi Villacampa, Joventut’s president, thinks Ricky Rubio’s words are nothing but a strategy to force his way out of the team.
Juan Carlos Navarro: “We all can see Ricky is nervous and worried about his future and we try to helo him any way we can.”