Guardiola worked with City's chief executive Ferran Soriano and director of football Txiki Beguiristain at Barcelona. He could reprise the relationship and take misfiring City to the next level in the EPL and in Europe, as Manuel Pellegrini is unstable.
Jose Mourinho could be replaced permanently by his nemesis, if owner Roman Abramovich can persuade Guardiola he will not resort to the axe if things don't go according to plan in the short term.
Louis van Gaal's position is not secure, with even sponsors Adidas criticising Man United's play. After David Moyes and the Dutchman, Guardiola could well be the successor to Alex Ferguson.
Arsene Wenger is in his 20th year as Arsenal boss and the Gunners will have the challenge of finding his successor at some point. If London is where Guardiola wishes to be, Arsenal may be a safer and more stable alternative than Chelsea.