Sacking him voided any potential compensation the English clubs would have needed to pay to poach Ancelotti, and not even Italian clubs are that daft. That said, as @Gotters posted above, the club is still a mess, even by Serie A’s low standards.
Last month there was a mutiny by the players, who refused to go on a training camp. Ancelotti had earlier stuck up for the players after disappointing results that led to the order to attend the camp. However, this stance was not reciprocated, with the players seen as turning their back on their manager. This compounded the sometimes fraught relationship he had with with several players, including club captain Insigne.
Attendances are poor for a club of their size and fanbase. Their ground, the San Paolo, holds over 54,000, but just 22,000 fans attended on Tuesday night in a game the side needed to win. After the training camp incident, the club’s Ultras reacted with derogatory chants towards the players. There was also an investigation as to whether midfielder Allan’s home was invaded as a warning. Several other criminal incidents against players have been linked with the club’s hardcore supporters. The club itself also threatened its own players with legal action over the refusal to attend the now infamous training camp.
The sacking has been building for months. If results were good the cracks behind the scenes could be papered over, but the side has dropped out of the title race with a string of poor results, which the Champions League progress only masks.
Going to Arsenal or Everton, both not without their own long-term problems, would feel like a luxury holiday for Ancelotti compared to the madness in Naples.