Anyway, I personally don't believe Zidane will become Manchester United head coach to replace Erik ten Hag. Because after all, the team which has a lot of money and also comes from the same country of origin as Zidane himself in France, but Zidane rejected PSG offer. Therefore, it seems that Zidane is only willing to coach in the teams which he played when he was a player, such as Real Madrid and maybe also Juventus in the future . But maybe, if Manchester United succeeds in bringing in Zidane as coach, then Manchester United will have a good chance of recovering. At least to get a trophy in one of the big competitions like the Premier League, because to getting the Champions League trophy will of course take time.
Well I don't believe Zidane would accept to join Manchester United cause the board themselves could ruin his good career, however in a worst case scenario where Erik Ten Hag gets sacked and Zidane finally agrees to join United then I think alot of agreement has to come in place before he even takes the offer, he'll need to be In charge of the signings and given alot of funds to help him improve his team, well it's not going to be easy if there's no transformation in the team cause alot of top managers have come and failed cause of that.
It's possible for Zidane to get a trophy at the team but consistency is what matters cause its been difficult for coaches to succeed at the club in their 2nd tenure cause of the way the board handles things in the club, they'll give him lots of funds for his debut season and failed to back him up in the next season to strengthen the club more.