The Arsenal full-back has been linked with a move away from North London.
Bellerin broke into the Gunners' senior side at the beginning of 2015 following an injury to Mathieu Debuchy, and he has not looked back.
The Mail reported this week that Arsenal were prepared to offer the right-back a new bumper contract in order to stave off interest in the Spanish sensation.
The jet-heeled defender, 21, has been linked with Manchester City and Barcelona (The Mail), having left Catalunya as a 16-year-old along with Jon Toral.
Arsenal's recent history is littered with examples of losing their best players well before they peaked, though manager Arsene Wenger has bucked this trend over the past couple of summer transfer windows by emerging relatively unscathed.
It will, however, be tough to keep Bellerin if Guardiola's City and Barcelona come sniffing around, but Mariner believes that the youngster will still be with the Gunners for the foreseeable future.
He told ESPN: "Debuchy was brought in a few years ago because Wenger wasn't quite sure about Bellerin, but in the end he has just took the bull by the horns and made that position his own.
"He's going to be there for a long, long time. He's got such a bright future. Fantastic full-back."
Given his age, combined with his talent, Bellerin might be Arsenal's biggest asset as far as value goes, but keeping him is key for Wenger's hopes of winning another Premier League title in the coming years.
Losing him may well offset the type of exodus which the club's fans are too familiar with over the last decade.