As noted earlier here on the website, Christian is scheduled to make another appearance in TNA Wrestling later this year at Bound for Glory to induct Sting into the TNA Hall of Fame. The appearance is part of WWE's agreement with TNA to allow Ric Flair to appear at WWE's Hall of Fame earlier this year. Christian is not returning to TNA full-time. This will be his final appearance as part of the Ric Flair/WWE/TNA deal.
TNA wanted Ric Flair to induct Sting but Flair's issues with TNA and TNA's lawsuit with WWE will likely prevent that.
Flair's four-month no-compete clause is scheduled to be up on September 6th. He'll technically be free to work for other promotions, but the TNA-WWE lawsuit will keep Flair (and Matt Morgan) out of WWE for a few months. WWE said in court they have no interest in signing any employees currently or recently under contract, and if they picked up Flair it would conflict with that and would obviously look bad in court. The feeling is that Flair and Morgan would have been in WWE within a month or two if not for the lawsuit. Basically, WWE isn't going to sign anyone associated with TNA until the lawsuit is finished. It's a smart move in the long run.
We'll keep you posted as we hear more.