There are literally hundreds of altcoins. This is why I believe speculating on domain names with them is worse than investing in them...
We're going to take Ethereum for example. If you had invested $20 (0.05 BTC) into an exchange on ETH, you would have gotten approximately 25 ETH at the beginning of 2016. That is now worth $270 (0.66 BTC).
Take that same $20 and purchase two domains. Compare it with the other once-popular altcoin Litecoin's historical domain sales and see that litecoinshop.com is the highest reported com sale at $311. If you had a hit domain out of the two that you purchased for ETH, you might make more money, who knows.
Another example is DogeCoin. You could've literally rode this one to the moon and made bank on the way. The only reported domain sale? DogecoinBot.com for $106 -- chump change compared to some Doge returns.
What is guaranteed is that you will make much more investing in the actual coin itself and hope it does succeed rather than following domain trends and investing in similar domains; the sales speak for themselves for every coin.
Just my opinion on altcoins and domain names...