Yes, I agree with your statement and I have personal experience with this statement. Actually now you can expect bigger returns in Bitcoin-like  x10 times or x20 times return from your investment. whereas Altcoins can give you returns like this from good potential coin something like i have experience with Neocoin few years back where i got almost x10 times to return from the investment in Neocoin. But yes i also  agree that in today's market conditions there are very less number of coins with good potential.