profit from coins depends on trading of this currency.If the coin was success and has a demand on crypto world then yes old coins are still profitable but if it has no demand on market and no trading traffic with this coin then it will bring less profitand slowly its price will discrease day by day But yes I will not say that old coins are not profitable any more,because in crypto market it is not so special that any coin goes on a top rank..suddenly..
and if doesn't happens then he can just sell those coins.