The problem with the altcoins is they don’t have the same popularity like bitcoin and don’t have that much business supporting them so people find places to spend their coins on, so with that even if they become viable they won’t have as much users as the bitcoin.
I kind of don't think that the popularity is the problem, but rather the user base. Almost everyone that's using bitcoins also know of ETH, Dash, and LTC, or any other major coins. They've heard of it and probably even know how they work but they are not using it. Altcoins are also pretty popular but people are far too loyal with bitcoins to get out of their comfort zone and start using an alternative coin.
However as the time goes by and people thinking that the bitcoin won’t last forever and it will become harder and harder to get they start switching to the altcoins and then they will stand a chance, but I don’t see that happening any time soon because most of the people are focusing on getting as much bitcoin as they can.
If bitcoin won't last forever, what will? Most altcoins are based on bitcoin's concept. Try looking at altcoins and see how many of them die every single day. Bitcoin is still the strongest one, as of now at least.
But alt-coin could have some bigger role in economy, like let's say theres an alt-coin made with sole purpose of paying really low costs like a few dollars and like that could be implemented in various businesses like coffee shops, but otherwise no, probably not.
