Yes, I am absolutely sure that many altcoins will successfully compete with Bitcoin in the future, especially if Bitcoin will not maintain its competitiveness. This is the law of any market and it is useless to argue with that. Bitcoin was the first type of cryptocurrency and therefore it has long been the most famous and popular. However, the world is constantly changing, along with Bitcoin, there are a lot of promising cryptocurrencies and the Bitcoin team will have to make a lot of efforts to keep it still for a long time the leader of cryptocurrencies.
How? Can you point out anything that you see that is the lapses of bitcoin, most bitcoin users has never got the reason to complain about bitcoin, and let me tell you something, most people that you see in cryptocurrency world today, came through referrals, and whoever is referring them uses bitcoin as the major tools of explanation, which is what will make the person pick interest in cryptocurrency, and if they are to invest.
Bitcoin will be the first coin to be considered by these people. So there is no way anther project can compete with bitcoin no matter how perfect the system might be, they will always see it as a clone of the original BTC.
he didn't say "today", he said "in the future" and i have to agree with him. bitcoin is great and compared to the other 2500+ altcoin it is the best cryptocurrency by far but it doesn't mean bitcoin is perfect. as a new technology there are a lot of areas of it that can be improved. so far many have tried, many others pretended to try but all of them have failed. some day a newer and better technology will come along just as bitcoin came along and made the centralized systems obsolete but that day won't come for at least another decade.