I agree to this. See, we already have a huge market created for crypto or say investment. Even if bitcoin dies tomorrow, that money will still be available to be invested in other options. People have got used to high returns and we will see developers coming with solutions to satisfy that need.
If bitcoin die, then there will be a negative effect on the altcoins price. Some people will lose their hope in cryptos if that will happen. But of course, as of the moment, a lot of people says that ethereum is the next to bitcoin. There will be a high chances of ethereum to increase its price if bitcoin die.
Anyway, I don't really think that's going to happen.