A lot depends on how useful is altcoins. Good altcoins that are useful for people will survive even in the fall of the market.
There are altcoins that offer cryptocurrency investment tools with crypto APP to work like S&P 500 like https://twitter.com/FiPiToken/status/1482266971731378177
Development of altcoins a lot will depends from the conditions of cryptocurrency market. If market will continue to rise people will invest more actively in altcoins and the development will increase.
During the dip of the market investors actively buy cryptocurrency assets. And dip of the market is a good reason to buy assets for the best price.
Also, during the fall of the market only the best projects will be able to survive.