We can see these days that not all people know cryptocurrencies, if they do perhaps they have heard only about bitcoin, but without owning or having the experience of making any transactions.
Maybe altcoins will become popular within 3 years from now?
When you mention cryptocurrencies, anyone hearing that already knows that youre not referring to just only one, although they might just know about Bitcoin and not others. Altcoins are not really meant to be known much, cause they are just alternatives, the main thing when we talk about crypto is Bitcoin and its not all altcoins that is going to last. There are already popular altcoins like ETH, Ripple, and BCH, and these ones are meant to stay alongside BTC.