Barton was told to stay away from the club following a furious dressing-room row with manager Alan Shearer in the wake of his dismissal in the 3-0 defeat at Liverpool, which ruled him out of the club's fight against relegation.
Barton, 26, is resigned to the prospect there will no reconciliation with Shearer but a legal battle could unfold if the club decide to terminate his lucrative contract that does not expire until 2012, although that could be averted if he is made available in a cut-price deal.
However, a source close to Barton told Telegraph Sport: "Any case of gross misconduct against Joey would be robustly defended."
Tottenham manager Harry Redknapp – who tried to take him to Portsmouth last year – and Blackburn's Sam Allardyce, who signed Barton for Newcastle, are expected to be among those brave enough to offer the midfielder an escape route from Tyneside.
"Some perspective needs to be put into this," the source added. "I couldn't totally rule out Joey pulling on a black and white shirt again, even if Newcastle are relegated, but it's probably fair to say that if Shearer is there he won't be and that will probably be a mutual decision.
"He's led a very quiet existence over the last six months. He's been exemplary off the pitch. He's still dry. There were no fisticuffs, none of the two of them fronting each other up or eyeballing each other. Joe's never short of an opinion but that's all he ever does in the dressing
Barton incurred Shearer's wrath after a crude challenge on Xabi Alonso prompted a three-match ban. That was followed by Newcastle's announcement the player "had been suspended from the club until further notice".
"The guy has continually bought Newcastle United into disrepute," former striker Malcolm Macdonald said. "In the short time he has been at Newcastle, he has either been injured, in prison or in trouble. Heaven help whatever club he does join."
Barton left as details emerged of Shearer's disciplinarian approach – including his '12 Commandments' that, for example, see players fined for tardiness.
A Newcastle insider said: "Alan may have been cracking the whip but it's long overdue. He's brought back discipline and professionalism that were watchwords for him in his playing days. He has laid down the law but the players have welcomed his approach and as far as they're concerned it's created a more enjoyable working environment.
"You can't have the lunatics taking over the asylum. You can't have people taking the ---- out of the club and Alan's determined that won't be allowed to happen. And with all the job losses around this part of the world, there won't be too much sympathy for players getting fined for being late for work."