The 29-year-old ended speculation of a return to former club Barcelona - who he left for a world-record £198million in 2017 - by putting pen to paper on a new deal worth £26million per season.
Neymar's contract had been set to expire at the end of the 2021-22 campaign but he has now agreed a deal which will see him through until 2025.
"The important thing to win trophies is stability in a group. To gain Neymar's loyalty even more, I think that's a very good thing," former PSG ace Ginola told France Info.
"Winning matches with one player today like back then, you could do with [Michel] Platini and [Diego] Maradona, I think those days are over.
"We cannot sign Neymar again without securing the signature of Kylian Mbappe. Neymar is 29 years old, his best years are behind him.
"Mbappe is more about youth, talent in its raw state, he is a boy who has enormous potential, but we are only at 60 per cent of his capacities.
"Except that today, all these players will have to realise that they can not win anything if they do not put themselves at the service of a group."