I think we come from different generations.
In my time, you never ever covet the manager of your closest rival. That's a big no-no.
This also used to apply to players, though this has changed a lot.
Do people remember the uproar created when Moyes declared that "MUFC aspire to play like MCFC"?
Another example: when Bill Shankley was LFC manager, MUFC fans would not compliment him and say, "I wish he managed us". It just wouldn't happen.
Similarly, with Matt Busby was MUFC manager, LFC fans would not beg him to join their club.
Pep made his choice, by joining MCFC.
Jose made his choice, by joining MUFC.
And neither of these managers will be joining the other club anytime soon, for reasons I explained above.
I am very happy that we got Jose and have no wish to ever see Pep managing us.
What I do want to see is Jose beat Pep and send him into a sabbatical...just as he did when he beat Pep to the title in Spain, which resulted in Pep quitting Barcelona.
Not disagreeing with you. In fact, i can understand where you're coming from and i agree with the gist of your post. But i think the general idea of the OP was to see what kind of reaction a possible appointment like that would provoke among United fans in the near or not so near future. Not to just "wish he was here" but to check if his time at City would make him a de facto persona non grata as far as the United bench is concerned despite his record. But i'm not blaming you for thinking that it is another ode to City, given the state of this place since the start of this season.
I think it's not easy to predict these things because situations change and circumstances alter as time goes on. A little more than a decade ago a certain individual, who was heralded as the next big thing in the managerial world, came to England and brought all his self-importance and his swagger with him. He also decided to become the spearhead in an oligarch's attempt to create a formidable force simply by spending big. He declared himself the "special one" and said "off with old". And the "old" in our case was United and Arsenal. He wasn't very liked at OT and when we won the league against him in 2007, it was really exhilarating. Soon after that, when he got the sack from his filthy rich employer who was looking for a new toy to play with, all of us thought of his sacking as Ferguson's and United's victory. I can assure you nobody wanted Mourinho here during that period.
A few years later we found ourselves in a weird predicament. Still trying to find our footing after Ferguson's retirement and taking wary looks over our shoulder because these days not even a place in the top-four seems secured in the PL. Suddenly, the idea of that certain individual doesn't look so appalling as it used to for many fans (of course some still don't like it). You can't predict how these things work.
Anyway, Shankly, Busby and Ferguson are all managers who have earned their own statues outside the stadiums of the teams they managed. It's not quite the same with Jose and Pep for me. It's funny because whenever i watch Chelsea, it's pretty obvious that he's played a massive role in reshaping the club's image. From the way the powers that be at SB select managers who don't deviate much from the principles Jose instilled to watching his later choices for them still being the backbone of the team and his former ones working as pundits under the label of "legends". You could see it yesterday too, how well "trained" (in a good way) the SB crowd is to anticipate a game with very little possession and 10 men behind the ball and how they got behind their team. Not so easy to do the same with OT faithful. At least not as the main plan. And yet, i can't associate Jose with Chelsea. Maybe it's because he didn't win the CL with them and somebody else did. I honestly can't say.
Right now, i feel the same about Guardiola. The only club i associate him with is Barcelona. When he was at Bayern and they faced Barcelona, not seeing him on the edge of Barca's bench felt weird. That's why i think that the only club where the fans would rather see their team relegated than Guardiola as their manager is Real Madrid. After he spends some time in Italy or France, i wouldn't mind him here. But, as i mentioned, things can change. If stays for many years at City and breaks more records with them (for example become the first manager to win four consecutive league title) and if he helps them make the real breakthrough into Europe's elite by winning the CL (God forbid), then yes he would have entangled himself with City in a way that would make his appointment much more difficult. Even by fans who sing his praises now, i assure you.
at that poster comparing Pep to Sir Alex. I like Pep a lot but in my eyes noone came to Sir Alex, not Pep or Jose or Wenger. He won it all with three teams he made himself and not only that but in the end he won it with players that weren't the greatest. I remember United beating us easily with a midfield of Fabio Brown O'Shea and Gibson 
No other manager could have done what he did. He's damn unlucky he came across that Barca side twice, he deserved more than 2 CL medals.