I don't think that case would happen in the market. Because as long as people innovate and try composing better coins new ideas will pop up and always come to merge and will become a new form of the future projects that investors may select.
It will never happen. more and more altcoins are getting introduced to the market and this time if it is much more frequent rather than last year. When there are a good coin and another developer will try to create the same coin but with better features.
This will never be stopped and will be last forever. We have bunch smartcontract right now.