Pep Guardiola will not join Napoli because he is on top of Premier League and Europe after last six successful seasons with Manchester City. He will not move to a smaller club like Napoli but it's possible for Mourinho to do this. With Mourinho, there is another barrier for Napoli to sign with him. He is experienced and smart enough to realize problems in Napoli so he will likely wait for chances from other clubs.
Haha you are right, it's impossible to see Pep Guardiola becoming Napoli coach. because Guardiola currently, like Mourinho, will prioritize a team that can meet the players' needs according to their wishes and whatever the price. If Napoli hopes for Guardiola, then Naples must prepare a big amount for transfer fee. I'm not sure Napoli can fulfill this. Moreover,
Reuters reported that Calzona is currently Napoli's new coach.