Arsene Wenger will have "no shortage of offers" for new jobs and is already taking calls from interested clubs, former Arsenal vice-chairman David Dein told Sky Sports.
Dein, who hired Wenger in 1996 when he was an unknown figure in England, also said that he debated with his old friend last season about whether he should stay on, and predicted that the 68-year-old will find life away from football "like a bereavement."
Wenger announced on Friday that he will quit at the end of the season despite being handed a new two-year deal last summer, with Arsenal limping toward their worst Premier Leauge finish of his 22-year reign.
"He will have no shortage of offers. I personally had calls from various people yesterday, asking to speak to him," Dein said. "So he won't be short of offers from clubs, if he wants the job.
"He's going to be 69 in October, but he keeps himself extraordinarily fit. He is the same weight as when I met him, 75 kilos. He keeps himself so fit. He's got a very active mind, such a knowledge of the game.
"And over the last few years, he has been approached by some of the biggest clubs in the world, Real Madrid, Paris Saint-Germain, the England national team wanted him at one stage."
Dein added that he was not surprised by the announcement and that he has had plenty of discussions with Wenger about whether it was time to step down.
"It's been coming. At the end of last season I was discussing with him, 'Arsene, what do you want to do? Are you going to stay? Are you going to leave?' He was a bit undecided," Dein said.
"In the end, I said, 'Arsene, do you know what your problem is?' He said, 'What's that?' I said, 'You love the club too much.' He's so attached to it. So loyal, so dedicated. He felt responsible for the players coming through.
"That was an option for him, undoubtedly. I was weighing up, 'If you leave now, this is the situation. If you go on, you roll the dice another year or two, what's going to happen?'
"He made his own mind up and decided to stay. I felt the last couple of weeks, it has been getting more difficult for him, particularly with the team results. I though that, on a personal level, it was unlikely that he was going to stay after the end of the season."
Wenger admitted on Sunday that life away from Arsenal will be difficult for him and Dein said he went through a similar challenge after leaving the club in 2007.
"It's going to be tough initially," Dein said. "As I found myself, it's a way of life. He's the first one at the club, the last one to leave. It will be difficult.
"It is rather like a bereavement and the various stages, the first one is denial and finally you get to acceptance and you move on. He has to have a good holiday and decide what he wants to do next."
Dein also paid a glowing tribute to Wenger's contributions for the club and hailed him as Arsenal's greatest ever manager.
"His legacy will be for global football. His style of play, the way he has conducted himself, his integrity, his honesty. The way he has handled players. What he has done for the club is immeasurable," Dein said.
"He will go down in history as the greatest Arsenal manager ever. We've built a fantastic training ground, sensational stadium. It was back on the Invincible team in 2003-04 that we managed to get financing for the stadium."