Ten Hag has indeed not made great achievements for Man United but I think he has made quite a significant change. So if he is still trusted to handle Man United for the following seasons, Man United will be a serious challenger in the Premier League. Man United need to get a new striker this season but I don't think they will be able to sign Harry Kane because the price is too high for Man United. Rasmus Hojlund is a pretty good option and the signing could be a great investment for Man United.
Kane wants to play for Bayern and Bayern remain hopeful of getting Kane. Kane's move to Manchester United seems unlikely to me, this is a rival team and even more so I think that he himself will not want to play for Manchester United. If this off-season does not work out with this transfer, then next summer his contract expires and then he can go to Bayern as a free agent, so Tottenham should also be interested in selling him before that time.