@Walrus
Fair enough, but I do think it's a bit disingenuous to club both Mourinho and Ancelotti in the same 2-3 year category. The reason I say this is, even though Mourinho has the ability to manage a team for 5+ years (might do so at Chelsea, we'll see), he was unlikely to do so (especially in the past, seems to have mellowed down a bit) because of his stubborn and volatile personality. Just like with his mentor Van Gaal, there's a risk of complete meltdown when things aren't going his way, and he morphs into an egoistic baby that threatens to demolish everything he built, and plants a seed of conflict at almost every club he manages.
Ancelotti meanwhile, is extremely serene by nature, and could be wrong here, but he is perfectly capable of staying at a club, and planting deep roots. The fact that he hasn't done so in the past (aside from Milan), is due to a mixture of him progressing to higher level with each change (Reggiana to Parma, Parma to Juventus, PSG to Real Madrid), or getting sacked (Juventus, Chelsea, Real Madrid). He is at a stage of his career, and life, where he has ridden the managerial carousel to its fullest - he has managed two of the biggest clubs in Italy (and categorically stated he doesn't prefer the culture of Serie A when questioned about a comeback), the biggest club in Spain, the biggest (at present) club in France, and Chelsea. If he comes to United, and succeeds, there is no incentive to him leaving the club, especially at a time when the Premier League is experiencing a financial boom, which should keep the club competing at the highest level year in and year out. Realistically speaking, which club would be an upgrade for him? He has been to Madrid, and Barcelona are unlikely to ever appoint him. And he's still just 56 years old, which gives him sufficient time to stay at the club for the long haul.
From the other premier candidates, Klopp has a similar kind of personality. Even though he's externally quite boisterous, Klopp really values a sense of loyalty, evidenced by his stint at Mainz, where he also spent his entire senior playing career (stuck around as a manager, even after relegation), and Dortmund (could have thrown a strop, and joined more higher profile clubs, but stayed, repeatedly said he intended on honoring his contract, and even agreed to a new deal, before ultimately splitting up with mutual consent). He's the type of character that like Fergie, or Wenger, would prefer to create a legacy at one club than shuttling around ever so often.
Here's a brief excerpt, kind of detailing into his arrival at Dortmund :
Taking over the reigns at Dortmund in 2008, the then forty one year old immediately fell head over heels. Surrounded by the best fans in the world, he started to reinvigorate the club, taking them to Supercup success in his first season and leading them to a respectable sixth place.
Sounds like the club we all support doesn't it? Honestly think he would fall in love with United for very similar reasons.
Bit more :
A passionate man, the former Mainz trainer often lets his emotions get the better of him, ‘we want to fight for our life, and we want to make our parents proud. We want to do everything we can to win this final. If we win, we are not the best team in the world-but we beat the best team in the world!’ he exclaimed before a cup game.
That highlights the fact that he's very much a family man with strong ideals, something that was reinforced by the amount of trust he put in his players, and the relationship he had with the fans.
Dunno why, but I get the distinct feeling that Ed Woodward would like to bring Klopp to Old Trafford despite the disappointment of Dortmund's 2014/ 2015 season, he's stated in the past that he really admired the German, and his body of work at Dortmund, even called him a genius in an interview with Mitten IIRC.
He speculated whether Jose Mourinho's CV could find its way back on a desk at Man United in the not-too-distant future but also added: "I know for a fact that Woodward has said that Jurgen Klopp is a genius and there is a clear admiration there."
http://www.newstalk.com/Will-Man-United-sack-Moyes-if-fans-revolt
Probably something to monitor if we falter this season, or Klopp is available whenever Van Gaal leaves.
Like you, I'm a bit more apprehensive about Guardiola, and whether he would stay 5+ years, to be honest. Apart from the burnout factor and exhaustive work ethic as you rightly mentioned, there's always the specter of Barcelona hanging around him, he might well decide to pack his bags and return home if everything falls into place, and his allies are on the board (despite public denials). Or he might even get disillusioned with football altogether, and walk away from management, bit like his biggest inspirations - Johan Cruyff and Arrigo Sacchi who felt they no longer had the burning desire to prove themselves, and wanted to leave at a relative high, maybe even venture into the administrative side of things.