I guess yes. Old coins are no longer profitable but not all. What remains solid in the coinmarketcap are those coins in the top list. So you can still invest in those old coins but choose the right one.
The age of the coin for me is not really the basis to tell that a particular coin will still profitable or will fully lost its value, what matters most is its movement in the market because its value is solely depends on the amount of supply and demand in the market and there are evident instances that there are old coins that will suddenly goes live and rising up its value because there are investors massively buy on it.