Manchester United are still entangled with Erik Ten Hag and they have not been bold enough to make that big decision to do away with Ten Hag. I think that should be the first step to take before wanting Simone Inzaghi who I also doubt will want a move from Inter Milan to a struggling club like Manchester United. Who will even want to leave a team like Inter Milan that’s doing very well to come and struggle at Manchester United and still face pressure of getting sacked if you fail to turn things around after few months? I don’t see that happening. Manchester United will have to look for another replacement for Ten Hag, why is Manchester United not looking inwards to get one of their former players to become the club’s manager like Ryan Giggs?
Manchester United will automatically be handled by their own former player if Ten Hag is fired, Ruud van Nistelrooy is now serving as his assistant coach. I agree with you, it is unlikely that Simone Inzaghi is willing to leave his position at Inter Milan and choose to move to Manchester United, especially in the near future. Management will bring in an Interim coach if they are not sure about Ruud van Nistelrooy, although in reality there is no guarantee that the scenario of firing Ten Hag can improve the team performance instantly in the near future. The pressure on Ten Hag is now increasing if Porto really manages to beat Manchester United in the Europa League, the current score is 3-2 for Porto victory. The match against Aston Villa may be his last match Ten Hag.
Inzaghi has already made a statement that he will remain at Inter and is not going anywhere including Manchester United so there is no reason for him to leave for now.
Van Nistelrooy can still be a consideration even though he is only an interim because he must have known how to work at Manchester United but in some rumors it is said that currently there are names that are associated with Manchester United including for Allegri and even Southgate.
Compared to Southgate I don't think he will be on the list especially his style of play will not match United but the possibility of Allegri can still be considered when there is no further agreement with Ten Hag then Van Nistelrooy or Allegri options can still be considered more by Manchester United.