The Reds appear to have brought any uncertainty regarding the future of their Egypt international future to a close by agreeing fresh terms.
Salah has regularly stated how happy he is at Anfield, with a 44-goal debut campaign having earned him hero status on the red half of Merseyside.
Barnes has, however, pointed out that money talks in the transfer market and with Madrid currently preparing to part with Cristiano Ronaldo, a sizeable offer from Spain could force any hand.
“Every club is a selling club. If Real Madrid offered £200m for Salah then he’d go and Liverpool would then be a selling club.
“Ronaldo might be leaving Real Madrid, [Robert] Lewandowski could leave Bayern Munich.
“Neymar could leave PSG as well so even the biggest clubs in the world are selling clubs.
“But what the new contract means is that Salah is committed to Liverpool and wants to stick around and see how far they can go.”
Lewandowski has sparked talk of interest from Madrid for some time, while Brazil international Neymar is also considered to be a future ‘Galactico’.
Liverpool, though, have no intention of parting with Salah and have him as a key part in their plans for 2018-19.
He will be granted an extended break on the back of his World Cup efforts with Egypt but will be back in the picture by the time the new Premier League campaign kicks off against West Ham on August 12.