Keane quit his job as Sunderland manager on Thursday, after 27 months in charge at the club.
Cascarino told Talksport: “He instigated the problems in Saipan in 2002 and got away.
“He instigated the problems at Manchester United at the end of his time there with the television interview he gave in which he criticised the players and he instigated the problems last Friday to do with his present team and I thought it was all so he could open the door to walk away.
“Maybe he doesn’t want to face Fergie this Saturday, maybe he doesn’t like the fact that Fergie might stare him down or think he got his comeuppance. Roy is a very difficult character to get close to and to understand.
“You don’t just go: ‘Oh I had a bad result today I think I’ll walk away.’ He has taken the easy option and not rolled up his sleeves.
“As much courage as Roy Keane thinks he has got, this was the end for him, he will not manage again.
“No one will give him the opportunity to manage their football club because they won’t trust a guy that is prepared to do what he has done three times: to instigate problems and then walk away.
“How are the board at Manchester United ever going to think Roy Keane ticks a lot of the boxes, because I don’t think he does.
“I think he gets an ‘x’ in a lot of the boxes. I think if he had held it together and kept Sunderland up and showed the way forward as a manager he would have had every chance.”