Bitcoin has been steadily losing market cap dominance, from 90%+ just two years ago to ~80% today.
When it comes to exchange dominance it's just 66.4%.
This trend will probably continue and in a few years there will be people using cryptocurrencies that do not know what bitcoin is.
I agree with you, when this trend continues. but people will still know what bitcoin is, because even though its value continues to fall, but bitcoin will still remain in the crypto market.