The market does not require a large number of coins. It uses only liquid coins. Every day more coins come on the market, but not all of them are needed. We already observe that many alts do not grow in the bull market. And I think that they will never grow up.
That's certainly true, mate. Most altcoins in the market right now are totally useless, since they do the same thing as other cryptocurrencies. Being copies of another crypto with no real uses or long-term vision for the mainstream world, will result in complete abandonment from developers and the community. However, those coins with a solid vision, constant development, and innovative features, will most likely survive in the future. For the useless coins in the market, we see a lot of them unable to rise in price after a bull market.
However, for altcoins that truly deliver the goods in the crypto space, they're always rising in price alongside Bitcoin in the market. Usually (but not guaranteed), the top 10-20 cryptocurrencies in market cap, will survive in the long term if they can keep up with constant development and innovation. Among the list, Ethereum is an altcoin which has a certain future, since it's always actively developed and supported by its community. Therefore, choosing altcoins which are similar to Ethereum, would be the best choice right now to preserve your investment in the future. Just my thoughts