Or any other alt coin for that matter? I'm wondering if and how it would damage/tarnish Bitcoin's reputation as the Gold standard of all cryptos. I believe it may also affect how institutions view bitcoin, and it may even affect the idea of digital scarcity. No longer can we assume that bitcoin (or its usurper) will remain #1 forever, so how can you imagine it as a safe long term store of value or preserver of wealth? Is the idea of true digital scarcity threatened if bitcoin loses it's #1 rank?
The sole reason that Bitcoin keeps on increasing it's value each and every year passed is more than enough of an evidence as to why no altcoin is a threat on Bitcoin's dominance in crypto market.
ETH has made a lot of changes and upgrades to fix it's scalability and everything, but it didn't even get near close as a threat to take over Bitcoin's spot.
Those questions you ask can be answered once It's actually happening.
Altcoins are not meant to replace Bitcoin their purpose is to give more options since Bitcoin is limited, that’s why altcoins was invented. I can’t see ang altcoins to be on top, if ETH increase its value I’m confident that BTC will pump and will still lead the market, BTC can’t be replace by any altcoins.