As Kane prepares for Argentina, Keane is spending the early part of this week at Champneys Springs in Leicestershire, one of 45 players taking part in the PFA's 12-week pre-season camp.
The initiative, now in its third year, is aimed at providing a competitive environment for out-of-contract players keen to find a new club.
At 33, Keane feels he has "a few years" left and has not abandoned hope of adding to his five senior Republic of Ireland caps, having made the reverse move of twin brother Michael by playing his youth football for England but seniors for the country where his dad was born.
"A couple of lads I know did the camp last season and spoke really highly," said Keane.
"I almost feel like I'm part of a squad, and we're away for pre-season. There are so many staff; medical, coaching, administrative, media.
"It's quite competitive and there are seven or eight games, so clubs can see you're playing. There's an app clubs can sign up to. It's like a PFA transfer list - all our training data goes on it. Clubs can contact us directly, so hopefully if you go somewhere, you can go straight in."
Keane is feeling quite relaxed about his situation. He was out of contract once before, in 2020, when Covid hit and Ipswich decided they didn't want to trigger a one-year option because of the financial uncertainties of that time.
Eventually, Keane went back to Wigan, one of eight clubs he has played for in a career of, to date, 335 senior appearances and 85 goals.
It was also the period when he altered his mental approach to the game.
That first devastating ACL injury would have been bad enough. But he also "ripped his groin" in United's FA Cup tie at Shrewsbury in February 2016.
It meant 17-year-old Marcus Rashford, not Keane, was on the bench for the Europa League tie against Midtjylland three days later when Anthony Martial was injured in the warm-up and had to pull out.
Given his debut by Louis van Gaal, Rashford scored twice and then added another two goals in the Premier League game with Arsenal that followed.
"I went to America for an operation, landed in Philadelphia, turned my phone on and saw he scored two more," Keane says.
At 23, Keane knew that day it was the end for him at United; the club he and his family supported, where it seemed so certain he would become a first-team player.
Worse was to follow.
"It was hard to take, but I had to move on. I got a good move to Hull, who had just been promoted to the Premier League," said Keane.
In his sixth game, he sustained another ACL injury and was out for 14 months.
"It was crushing," he said. "I missed the whole season, and we got relegated. A lot of the young lads still got good moves; Harry Maguire went to Leicester, Andy Robertson went to Liverpool, Sam Clucas to Swansea."
