I think Poch would be the next in the line of failed managers, for a number of reasons.
The guy was obviously burnt out for one. He likely needs an extended break at the very least before he'll be back to his best.
Secondly, I don't think he's got the personality to cope with the pressure of a dysfunctional United. It takes a special kind of character to sustain any kind of success at the high-end of football, and I don't see that in Poch at all. He doesn't seem to have the grit, the obsessive determination of a SAF or a Pep. He also appears to have his heart set on Madrid, which sort of adds to that worry.
Last of all, I think what we've been crying out for since SAF is not someone who's 'Been there and done that', but someone on the way up, who's developed just the right base of knowledge & experience while still having the energy and desire to prove himself (Ala Klopp at Dortmund). Someone with a positive tactical approach and the ability to imprint it quickly, to bring back a bit of character to our club. Maybe Poch is that guy? I personally don't see it.
I don't watch enough football outside of United to say who that guy could be really. Rose & Nagelsmann both seem like strong candidates, playing good football and punching above their weight in Germany, but I don't see us landing either. I'm sure there are plenty of similar up and coming managers flying under the radar, if anyone can suggest some names?
I hope Ole pulls it out of the bag of course, but signs so far don't bode well on that front I'd say.