That might be true. But I do not believe Ethereum will be able to hold their gains for long. Sooner or later the price has to go down simply because that is what markets do.
So always remind yourself not to get lost in the mania and try to stay objective. In a market like this, it is easy to think that the good days will never end.
Yes it will be stay as number one for long because maybe they can find another one which is better than bitcoin. No one knows what will going to happen next. It is possible that another cryptocurrency will rise and replace bitcoin as a number one.
The possibilities are there other digital currency may replace bitcoin. But as per now, there is no other currency near to touch bitcoins. It went a long way, and it keeps on moving. So I think no other altcoins will replace bitcoin. This is just my opinion. But ETH is actually giving a good fight to bitcoin. Within a short period, it improved a lot. Let's see what happen in future.