Ramos has had one of the most decorated careers of any player who has represented Los Blancos.
Real broke the record for a Spanish defender by paying €27m to sign Ramos from his boyhood club Sevilla.
Switching between right-back and centre-back in his early years, Ramos was a star for Spain and helped his country win the World Cup in 2010, and the Euros in 2008 and 2012.
In his 15 years with Real, Ramos has won five La Liga titles and four Champions Leagued crowns.
But the 34-year-old has less than a year remaining on his current contract with the club, leading to questions about his future.
However, according to Milla, who won two league titles with Real, there is no chance Ramos will leave the Bernabeu.
"Like Casillas and Raul, Ramos is an emblematic player and I would like to see him staying on at Real Madrid in some sort of role for the club after he retires as a player."
For Real's part, it appears they are also keen to extend Ramos' stay.
"He will continue as long he wants to, he knows that. As long as he has the desire to stay with us and has the strength to continue playing, I think he will stay with us for many more years."