Keys, who resigned from Sky following Andy Gray's dimissal over sexist remarks they believed were off-camera, now works for Al-Jazeera in Qatar.
And the former Sky presenter said in an interview with The Independent that, while Carragher and Neville are gaining plaudits now, their success will not last.
"When [Sky Sports] were signing left, right and centre, I said, 'I wouldn't do that'. Sky have done their money. They've done their money on [Gary] Neville and [Jamie] Carragher and [Graeme] Souness and they haven't got the money to pay anyone else. And with the regularity of those three, the novelty will wear off.
"I just don't know if that formula works the way they want it to now. We used to bring guests in occasionally when Andy and I were doing it. It never worked. Too many people in the same place trying to say the same thing."
Keys does take credit for Sky hiring Neville, however: "He was my idea. Me and Geoff Shreeves. We sat with him in Manchester over a bowl of chips. We went and saw Giggsy over the same weekend and said to them both, 'Whichever one of you retires first, come and join us'. I went to [then-Sky managing director of sport and news] Vic Wakeling - Shreevesy was as much a part of it - saying, 'One or other of those two would be perfect'."
Keys believes he will be working with a better class of pundit in his current job.
He said: "We have had a whole host of people come and see us. Keegan, Shearer. Hoddle is coming. We've had Peter Reid. We've had David Platt. Peter Schmeichel is coming. Terry Venables is coming.
"David O'Leary has just come back. Mark Hateley has been here. You name them. If they haven't been, they will be coming."
Keys is also happy not to be living with the British press, anymore.
"They say we have a free press in the UK. I'm not sure that we do. We have a press owned by too few, that can manipulate public opinion any which way they like.
"I am pleased not to be part of that, it's a huge thing for me, to live in a country now where that sort of hypocrisy doesn't exist. It just doesn't exist."
Keegan. Shearer. Platty. All the big guns right there. What a dreadful man.- benvo81