In the end, they will simply bring their own value down. I for one has had enough of this game.
BTC shoots up, Eth follows for a short while and move sideways, and even drops. BTC drops, Eth crashes. BTC goes up, Eth slowly follows but nothing stellar. It seems like Eth has lost its steam. Same with LTC. Neither seems to actually breaks through. Both lost huge percentage in value relative to BTC. Yeah the news and hype says - Eth and LTC is now - really this time - going to break out.
But then it seems like BTC just sucks the air out of them. Last few times, this time. If the pattern is not broken then I think Eth and LTC is just doomed to show small gains and just lose out to BTC.