I don't see it. I think United have a systemic issue where SAF/ squad of 92 looms over them.
They've hired LvG or Mou over the last few years and they've done basically what Ole has done.
I also think their players are overrated.
Both LvG and Mourinho were/are past their best when it comes to club football. Still good for NTs though and I bet Mourinho would make a very good NT coach.
It can go either way. They have some real talent and money to invest, but they need someone with a plan. OGS is just not that. You can play much better with this group of players. Whether that results into major trophies like the PL is another discussion, but there is def a possibility to play better and compete better.
We could also play better and compete better with a better manager. I'm not saying we'll become CL contenders and win La Liga, but you cannot tell me it's not possible for the same group of players sans Luuk de Jong to play much better football.