Uruguay striker Suarez is serving a FIFA four-month ban after biting Italy defender Giorgio Chiellini during a group match at the World Cup in Brazil.
He will sit out a further nine games through suspension which affects the Reds, who are set for a more demanding campaign with UEFA Champions League football.
In his column for the Mail Online, Ferdinand believes the Merseysiders should target Alexis Sanchez as part of a deal with Barcelona, who have shown interested in Suarez.
“If I were the chief executive or the money man at Liverpool, I’d have him up for sale already,” the 35-year-old centre-back wrote.
“The issue is one of risk and what might happen in the future given a pattern of behaviour. Keeping Suarez may potentially cost Liverpool tens of millions of pounds. Perhaps 70-million or more.
“How so? If he went somewhere else this summer – Spain, I guess, with Barcelona and Real Madrid showing recent interest and having the money – Liverpool cash in on their biggest asset.
“Yes, it will be a tough ask to replace such quality, but if all the proceeds and more were re-invested in a proven striker, it might make sense.”
Ferdinand added: “If Liverpool don’t sell him and he bites someone else after his ban ends, he could be thrown out for years. The solution to the Suarez situation could be that if Barca do want him, I’d demand Alexis Sanchez in a swap deal.
“If I were the Liverpool manager there wouldn’t be a moment’s doubt about what to do next with Luis Suarez. I’d keep him.
“Leave aside, just for a moment, questions of morality or whether his ban is long enough and what is going on is his head to make him do these extraordinarily bad things.
“Purely and simply from a football perspective, what he does for you on the pitch – and I don’t mean biting people – makes him indispensable.
“And with the season Liverpool have ahead of them, that’s truer than ever. So that’s the football decision. It’s an easy one to make.”