I think it's more than plausible to suggest a potential new owner would bring their own people in. But if it's a choice between Richard Arnold and John Murtough, then it's John Murtough who should stay imo, and he would provide a stability on the football side of the club which Richard Arnold can't provide. Murtough is a football man and has a long history of developing and modernising football clubs on the structural side of the football club. And he's not a remnant of Woodward but was brought to the club by David Moyes to revamp and develop the scouting and youth development side of the club which had fallen behind the competition. And whatever anyone says about David Moyes, he was the most clued on manager we've had as far as understanding the structural side of a football club in the modern game. And he was attempting to modernise the structure throughout the club but unfortunately he wasn't good enough to keep his job.
So if a potential new ownership group brings their own people in, then fair enough. But if they do bring in football consultants to review the work of the people already at the club. Then John Murtough's work mainly at the development level and creating the strategy for the club's first data science team on the football side of the club is good imo. Murtough has spent most of his career at United developing the youth teams which were said to be in a very bad state before his arrival, and he's done well in that regard.
And just because Woodward and the likes of LVG, Mourinho and Ole made a mess when it came to first team recruitment, doesn't mean we should blame Murtough at youth level. Because at youth level our recruitment has been good and the players Murtough signed, like Hannibal, Garnacho, Mainoo, Gore etc will at the very least bring in a considerable amount of money via sales if they don't make it as United first teamers.