Bitcoin will grow no matter how much a certain altcoin is being pumped. As with all altcoins, they will get dumped to the ground at some point. Ethereum is definitely not an exception. New money will be attracted by the volatile nature of Bitcoin. The market takes care of itself nicely.
I agree. Due to the network effect (advantage of being first coin in the block) Bitcoin is independent from the other altcoins, and other coins depend on the price of Bitcoin.
It is hard to know when Bitcoin will rise and that is almost indeed unable to predict because it is a currency, you never know what can happen what will happen next.
The most people are even thinking that the value is not even rising now and that it will take a long time to have that such a high value.