I have no deep knowledge with Bitcoin because i have never research it.But i know something about alt coin and it will be fully depended on ethereum.When eth price is growing than alt market is pumped.In the last month of the previous year ETH touched 1200$ when all alt is pumped a lot.
When you said altcoin is depending on etherium price yes it might be true.
We know etehrium price is not depending on bitcoin but sometime when bitcoin goes up, the value of etehrium also increasing in order to compare with fiat