It is possible for new coins to reach top 20 list. Uniswap and Sushi are quite popular these days. I wonder if these coins will remain their position in the top 20 list.
The market cap is large but does not mean its value is forever high. In the crypto market there are always horrible manipulations, just like in 2017.So be careful when determining to hold those tokens long, as it only appends based on the defi trend. but the trend can be lost at any moment, the sell-off will happen soon.