I don't think so that altcoin topple bitcoin. Although Altcoin are good profitable markets coin but they are still upgrading currency, where as bitcoin is a fully upgraded currency. Bitcoin price is too much high then that of Altcoin. In the case of price no single altcoins have potential to beat bitcoin. Because of its price bitcoin is the first choice of many people for investment or for other purpose. Many people use it for investment purposes too instead of altcoins. And another reason which help bitcoin to beat altcoins is its acceptance in multiple countries then that of Altcoin.