That is the trend, when bitcoin rise the rest will follow, maybe it's the reason why altcoins name was created because bitcoin is the most dominant
of them all, hence we call it the king of crypto. As an investor, I did not long for my coin to exceed the success of bitcoin because I am already satisfied if it will ride with the success of bitcoin.
Absolutely not. Bitcoin solves a real problem - trustless and censorship-resistant transfer of value. Almost all ICOs either invent a problem, to make a case for the token sale or declare (declare! not actually build!) to disrupt an activity(absolutely stupid term).
There is absolutely no reason for even 20 tokens to exist as major independent tradeable assets.
When Bitcoin starts to take off longing resistance, altcoins will get smoked - the situation is no way the same as in November 2017. If it happens simultaneously with a strong SEC statement of all ICOs being unregistered securities, we will see cascades of blood.