IMHO if ETH fills the small(er) transaction / sale void (fast/low gas) left by BTC, it will eventually eclipse BTC.
There is NO hard floor price for BTC.  This is a dangerous time for BTC...while BTC's retail acceptance is the largest, it is by no means mainstream and another one could replace it...

A couple of months ago:

Q: "Why is BTC going up so much?"
A1:  "Because it has the widest acceptance of all the cryptocurrencies"
A2: "It is going up because it is going up - it's called the FOMO-Kardasian effect"

Current day:

Q: "Why did BTC drop by half?"
A1: "Typical market correction after big run ups"
A2: "Transaction fees / times are too high/long and this is affecting BTC's value as a usable crypto"
A3: "People are suspecting market manipulation"


Years from now:

Q: "Why did BTC die?"
A1: "The first one usually does"
A2: "ETH (or other) became more useful as a daily currency and so the user base just kept growing, passed BTC, and became dominant.  
 BTC could only be used for specialized, large transactions but ETH could be used for everything big and small."
A3: "BTC never escaped being just a novelty/curiosity to the mainstream, other cryptos gained daily value and usage"