Mancini heads into Sunday's Manchester derby only three points adrift of United and the only unbeaten side in the entire English four-tier structure.
Yet the Italian is under pressure following the Blues' European exit, their defeat by Borussia Dortmund on Tuesday meaning they have not even landed in the Europa League following their Champions League exit, as was the case 12 months ago.
Neville believes an FA Cup and Premier League underline the progress City have made over the past two seasons.
However, with a new chief executive to impress in Ferran Soriano and a new director of football to work with now Brian Marwood has made way for Txiki Begiristain, he feels Mancini's position cannot be described as secure, especially with Pep Guardiola and Jose Mourinho likely to be looking for work in the summer.
"Roberto Mancini deserves more time but it is not a ridiculous suggestion to think City would not consider making a change if he doesn't win the league," said Neville.
"Whilst Roberto Mancini continues to be successful he should stay in his job but it does feel like one day Mourinho or Guardiola will end up there.
"They have a new chief executive and a new director of football who presumably have the ear of the owner.
"It might be three or five years but eventually they will want to stamp their mark on the club and Mourinho and Guardiola have to be pretty high on the list."