Honest question, why would he go to Utd now? Not being funny but Utd are around Spurs' level in the league - the move to City I could understand, but why would he leave to a club that is currently really no better on the pitch than Spurs?
Yes 100% certain he would for a number of reasons.
Kane has one chance left at a big move, United can blow Spurs out the water and offer him double anything that Spurs offer him.
United are clearly on the way up, whereas Spurs are on the way down. There are question marks over how long Conte will be in charge with his negative style of football whereas Erik Ten Hag will be here long term playing progressive football. United could win the league next season just by adding Kane.
Kane is still angry that Daniel Levy refused to allow him to move to City, so why on earth would he stay any longer than he has to? If he was going to sign another contract at Spurs he’d have done it by now. The Bayern rumours are interesting. It wouldn't surprise me if Levy has already approached Bayern to offer him to them.
Lack of options. He won’t go to Chelsea or Arsenal, Liverpool can’t afford him plus have just spent big on Nunez, City signing Haaland means that Kane has missed his opportunity to join them, so he has to decide what his next best move would be. He wants to stay in the Premier League so that only really leaves United.