I didn't say he was joining Dortmund, I said that both he and his dof didn't make a verbal commitment to him staying past this season when confronted with rumors.
And for what it's worth I wouldn't be surprised if United's troubles of the past would be a turn off rather than turn on for fresh coaches like Rose and Nagelsmann, who are used to working alongside a strong recruitment structure that built a cohesive squad for them and might associate United's lack thereof with a high risk to get burned early in their careers.
The players that Rose and Nagelsmann are used to sign aren't difficult for United to get. Do you think United would have failed to close the Sancho deal if he cost £50m? And besides, in Rashford, Martial, Bruno, VDB, Maguire, AWB, Shaw, Telles, Tuanzebe and Greenwood we have the foundations of a good team that needs a couple of class additions to be competitive.
We no longer need a window where we have to sign five or six players and we have some exciting prospects coming through the academy. We are not in a bad place at all in terms of playing resources and the challenge of turning around this club could make someone a managerial legend, not to mention the pay package.
The major challenge with United is that we are reactive so someone will notice him, think Barca, City, Juve or Chelse, whilst we dither with the decision to sack Ole and by the time we finally come around to making a decision he/any other promising coach would have signed for someone else.