I don't think any altcoin especially ethereum will be able to match or compete with Bitcoin's reliability or its value. Bitcoin has proven itself to be amazingly incredible over the years and yes Satoshi himself gave it a huge head start, many altcoins have emerged, yet Bitcoin has remained the most recognized and valuable cryptocurrency, it's dominance is unmatched. Over the years Bitcoin has managed to maintain its position at the forefront.
Bitcoin have proven itself to be among the best over the years, people seems to compare etherum and see it as a rival base on the influence and it also being the most popular coins when it started and how it have brings a lot of project under it is something that others consider as being influential but in terms of value and usage it cant be compared to bitcoin it lack they features being centralized alone have disqualified it from the competition.
Bitcoin will continue to be the best, and no altcoins can pose a threat to Bitcoin. Bitcoin will continue to move smoothly and without stress, because if altcoins could pose a threat to Bitcoin, they should have done so years ago, but he has become the best, and no coin can overtake him currently. We don't know what the future holds, but I don't believe they will ever have a coin that can overtake Bitcoin. Bitcoin will continue to grow, and years by years, he will become more merciful and continue be the leader of all coins.
That is why even some government is trying to make Bitcoin down, but because they don't have the power, they are still strong and they can never achieve their goal, since the don't have access to it. And no one knows when the price will increase or decrease, and that makes it the best in crypto investment, unlike altcoins that misbehaved and you invest and later drop, and he will probably not raise again, and you will total lose all your funds. but Bitcoin will never make you lose all your funds because is the best coin and he didn't drop down like other coins and anytime he drop just be expecting it that he will surely increase, and you will get your capital and profits.