#1 Mourinho out! Then who?
Here are potential big names who the hierarchy might consider.
Mauricio Pochettino
The Spurs boss Mauricio Pochettino seems content in North London. He previously was reported to have rejected an approach from United after they sacked Louis van Gaal. There is no reason for the Argentine to leave Spurs for fellow Top 4 challengers. The only benefit would be a higher transfer budget. There is no guarantee that he can turn the fortunes of United around quickly from Manchester United's perspective.
He was afforded two seasons at Spurs to change things around before the results started coming together and his side seems capable of challenging by themselves.
Most important is the Daniel Levy factor. It seems impossible to see Levy allowing his most prized asset to leave the club so soon after the New White Hart Lane is inaugurated to a direct rival.
Zinedine Zidane
Zidane left Real Madrid after becoming 'burnt out'. There are more than a few sources which say he left after realising he might be sacked.
At United, Zidane would gain the respect of players. The job at United though requires more than man management.
Zidane's style of play depended highly on allowing his explosive frontmen at Real Madrid to express themselves. When they were out of touch, he seldom showed tactical nous to rescue the side.
In the age of an inspired Manchester City dominating the League, it is risky to go all in for a manager whose skill-set revolves around managing egos and not tactical acumen.
In fact on balance, he would be a better replacement for Guardiola at City, considering the kind of skills needed at the Etihad in the long run to preserve a star-studded squad
Zidane also knew Real Madrid inside out. This was a result of having been a part of the coaching staff for a long time.
While his achievements are not to be scoffed at, his skills do not transfer to the Manchester United situation. This is because of a need to improve the squad and rebuild it in his image. There is no guarantee that Zidane's rebuild, should it happen, will deliver results. As it has been seen over the course of the last two rebuilds at United, 'philosophy' doesn't guarantee results or style.
Zidane still has a lot left to prove, despite his back to back Champions League titles.
Other names
Simeone is the biggest name left. Ancelotti, whose career graph fits Old Trafford only recently moved to Napoli. Thomas Tuchel took charge of PSG this summer. This leaves Simeone and Allegri as the only names that fit the profile of United, provided they are interested.
The other choices would be unconventional options. However, both Allegri and Simeone play a brand of football similar to Mourinho. Their sides are focused on solidity and counter attacks. Appointing them will not change much on the style front.
Leonardo Jardim suits United's core philosophy. But, he would require time to implement his ideas. Time is the one commodity United can't afford in the age of City and a strong Liverpool.
Mourinho guarantees results-now. Results till 2020 will give them a solid platform to build on again.
There is a chance, the future will bring more options for the Board. Until then, Mourinho is their best shot at glory.