I think that is the case, untill a coin is found that is significantly better than bitcoin, not just another copycat.
A coin that can do something fundamental, that bitcoin cant.
Pretty much this.
All the altcoins are just copies of BTC but the problem is that so many people are using BTC already that the value is significantly higher than the value of the other coins will probably ever be. BTC is bigger
and is growing stronger.
I see no reason to invest in any other coin, unless it turns out Bitcoin had some flaws that make it unusuable.