bitcoin without altcoins is just like dollar without poundsterling, euro, or anything else.
to trade a commodity, we need an alternate to compare the quality (price) when it flooring on the market.
yeah to make bitcoin to the top cryptocurrency it needs alternatives to compare. The reason that it will be extremely difficult for any altcoin to gain a larger share of the market than Bitcoin is the reality that Bitcoins much larger market cap is actually what allows it to hold onto that top spot.