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?
Well, here, I think everything will depend on the developers of coins, if they are determined and they have enough experience in this field, I think they can bring their offspring to the market as soon as possible, but if the team wants to raise only funds for their enrichment, then 3 years will not be enough.