Of course it doesn't have to be Southgate. I just talked about it because of the recent rumours going around.

There are surely better options with really good careers.
I have already mentioned Conte as an example. He is familiar with the Premier League already you know. He has a nice history with Chelsea like winning a Premier League and an FA Cup titles. Maybe he would be considered as one of the candidates in case of deciding to sack Erik ten Hag. However there are new rumours like Sir Jim Ratcliffe can give another chance to Erik ten Hag for next season. If this happens they had better make their transfers properly in the summer.
Manchester United will be damned if they think that Gareth Southgate would do a better job than Erik Ten Hag in the long run, then they must be fucking blind.
England manager and he is yet to win a single trophy with the national team. Is this the so called coach that would defeat Manchester City, Liverpool and also win Manchester United the Premier League and the Champions League Competition? They shouldn't forget that no English Coach has ever won the Premier League Competition and Gareth Southgate would be of no good use. Both Michael Carrick and David Moyes are far better than him.
Antonio Conte works with already made players, I see that the plans of Manchester United would be to develop youngins just as Sir Alex Ferguson did with the 92 set of players and ahead.
Erik Ten Hag or Roberto De Zebri would do grand. But how good is Zebri if he handles a top club like Manchester United?