Is Ethereum and other altcoins taking over and replacing Bitcoin?
If so, how fast will this happen?
This is a long process for Altcoins to catch up with Bitcoin. You can judge for yourself the different interests of the 2 currencies. although there is a coin price that can catch up with Bitcoin but will not have any effect on Bitcoin. Bitcoin has its own place for people to invest in. Belief in Bitcoin will be much different from other coins, especially in coins that are just emerging on the market. With the increase in Ethereum does not mean Bitcoin will just sit there until the coin has no numbers. It's impossible
I do not think that it is even gradual; there is no possible way that any other coin replace it. I get that bitcoin went down to 45% dominance and I get that it is 54k right now with 7% or so drop, and I can see that ETH had a great period and it increased all the way to 3.3k and beyond, with ETH having 17% or so dominance all by itself. These are all things that make it look like there is a chance that ETH could overtake bitcoin one day, and it looks like there is a possibility.
However remember that bitcoin has 1 trillion dollar marketcap whereas ethereum has less than 400 billion dollars. Which means it needs to go up 2.5x more on top of what it has already gone up, and that will result with the increase, that is not really possible without bitcoin moving at all. I believe it is going to be a lot more challenging then what we have seen so far.