I think only some useless altcoins will die.
Do you think all altcoins will die if bitcoin reach $100k?
I don't know what kind of aspect when said useless altcoin. Some of altcoin many kind of aspect like, economic, influencer, finance, tech and anything. all of them usefull when altcoin to apply one. when bitcoin reach 100k, no problem with altcoin, it will be followed.