I am not using any other crypto currency at the moment, but I don't think any of them will ever overtake bitcoin. Its the standard of all, its like money now, do you see money competing with anything else? I really don't see that. So I feel bitcoin will hold it own in the market and would probably keep growing.
Though bitcoin is the pioneer of the all the cryptocurrencies, some of the altcoins can bypass bitcoin price wise. Money is a currency so is bitcoin. Bitcoin is a digital currency. Lets take pounds and dollars for instance, one is heavy than the other in terms of their value so money do compete each other.