I don't think if you check the market cap there a lot of cryptocurrencies, that are gaining support and interest from the community, and there are a lot of cryptocurrencies that keeps on developing their products and platforms, cryptocurrency is here to stay and they are going to stay alongside Bitcoin.
Increasing market cap doesn't guarantee anything. And for many of the lesser known altcoins, a large part of the circulating supply is not in free-float, which means that these coins are not actively traded. So the market capitalization calculated by coinmarketcap may be inflated. Right now, I would say that the market cap stats are accurate only for Bitcoin.