I don't think it will affect Bitcoin negatively since altcoins will also use Bitcoin as one of the trading pair in crypto exchange this may help increase the demand for Bitcoin. And altcoins has usually unique service that may not hinder the growth of Bitcoin so for me the effect maybe more on positive rather than the negative side.
Exactly mate. Well, as we all know bitcoin is a dominant crypto currency in which most altcoins relying on its value. I don't think it is a threat since as we know altcoins is very far on it's capability compare to bitcoin but in some point it will depends on the demand of many users but for me bitcoin is so great among other crypto currency here in the cyberworld.