Its impossible to have one or two coins in crypto space because one or two coins can't solve all the problems we have in this world in every aspect of technology or others, if you want to keep a coin for a long time make sure the coin or token solves one or two problems in crypto space or the world, this type of coins don't die easily because they have real use cases, its simple as that
This is the beauty and diversity in the use of cryptos this is were research will come into play, So many projects out there are mainly for problem solving however choosing the right coin with a future prospect is the major task, of course bitcoin and ethereum are already established and prosperous coin I would have prefers a coin whose value is at the lowest ebb but with a good project and prospect for investment.