I think that's a really good point. I don't know whether those clubs you listed were just lucky, or whether they had a vision which extended beyond short term results.
When Mourinho was appointed, it was clear to almost everyone that it wasn't an ideal fit. The gamble was that he would halt the decline and bring in the big trophies in the short term, and there would be time later to repair whatever damage had been done to the club. It looks like we've now reached the point where winning more big trophies look unlikely, and the damage being inflicted on the club is painfully obvious.
Our next appointment should be one that seeks to re-establish the image and brand of Manchester United. The brief included in the job description should emphasise the things that originally made our club great - a commitment to exciting football, and to nurturing and promoting talented young players. The new manager, whoever he is and whenever he is appointed, needs to be told that he will be given time to achieve results as long as he works within those parameters.
As fans, we will need to be patient. We are some way away from being in a position to challenge for the league, and we're not going to close the gap in the short term through a series of fantasy football signings (there are clubs that can match or surpass our spending, and we're no longer a great destination for ambitious players).