"We do not see any top talent coming up to replace great players like Muttiah Muralitharan and Kumar Sangakkara," Ranatunga said at a ceremony to commend Muralitharan on becoming the world's highest Test wicket taker.
"They cannot go on forever and ever.
We need players to replace them."
Muralitharan is in the twilight of his career at 35 while both captain Mahela Jayawardene and prolific wicket-keeper batsman Kumar Sangakkara are 30.
Aggressive opener Sanath Jayasuriya, Sri Lanka's highest scorer in both forms of cricket, retired from Test cricket last week at 38.
Ranatunga, who led Sri Lanka to its only World Cup win in 1996, also said that veterans had begun to feel the need to nurture local talent and want structural changes in the domestic game.
The outspoken Ranatunga has often expressed dissatisfaction over the deteriorating standards of the game that he claims is the result of cricket administration falling into hands of businessmen.
The left-handed batsman who reti