Southgate wouldn't be my first choice, but I will say I think the job he's done as England manager is far better than most give him credit for. Hard to judge how he'd do in club management since the 2 roles are so different, and he only managed one club before (and it was ages ago). He's undoubtedly learned a lot since 2009. Whether it's enough to succeed as Utd manager, I'm not sure, but there doesn't seem to be many realistic options.
Alonso certainly seems out of the question (unfortunately, as he would have been my first choice). Brighton's defensive frailties this season have given me doubts about De Zerbi. I think Tuchel's a great tactician, but it can't be denied that he's fallen out with a lot of different squads now, and I certainly wouldn't call our bunch a particularly professional lot. Maybe Nagelsman, but aside from that, not sure what the alternatives are. Perhaps Xavi could be a shout?
I definitely don't want ETH here longer than the end of this season. Amazing FA Cup moment aside, our defensive weaknesses this season have been completely unacceptable. We're among the absolute worst defences and despite the criticism Onana's got, he's actually prevented more goals than nearly every other keeper in the league.
England have generally looked pretty defensively solid whenever I've watched them. Maybe that's what interests Ratcliffe and the rest of the backroom team. Theoretically, if we could become more defensively solid and well-organised while maintaining the attacking talents of Mainoo, Bruno, Garnacho, Rashford and Hojlund (maybe adding Joao Neves if rumours are true), you would expect us to look significantly better. There's still a lot of individual talent there.