The 18-year-old has been one of Watford's star players this season following his loan move from Stamford Bridge last year.
The Hornets just missed out on automatic promotion to the top flight last weekend and now face a crucial play-off against Leicester.
And the Watford boss has made it clear he would like Chalobah to stay at Vicarage Road next season, with Premier League football making this more likely.
Zola said: "If we go up to the Premier League we stand more chance of having him here for a longer period but right now it is impossible to say.
"It is difficult to know because it depends on the manager who goes to Chelsea and many other things."