What will you do if some altcoin (XMR or ETH for example surpasses the value of BTC, either in market cap or by the price of a token each? Will you sell your BTC to buy the more "valuable" coin, or continue using and holding BTC? Also, what do you think are the chances that it could happen? I would like to hear your thoughts and opinions.
There are a lot of implications actually but if the value surpasses bitcoin, then it would replace bitcoin as the reigning cryptocurrency in the market. There are a lot of factors to consider especially if an altcoin surpasses bitcoin in value. If in the price graph it showed tremendous skyrocketing of its price, then people would prefer that altcoin compared to others, thus increasing its demand and supply in the market. Basically, what will happen to that altcoin will be the thing that is HAPPENING CURRENTLY into bitcoin.
A lot of professional market/trader analysts would discuss and give their opinions, banks would shift their focus into that altcoin and governments would see it again as a boon or a bane towards the economy.
I think it's not easy to surpass bitcoin although we can't say that no other crypto will, because in crypto world there are many competitors aiming to be the highest value of crypto. So if there are so many cryptocurrency then it would be hard to surpass bitcoin because the popularity is devide.
Typically, the price of bitcoin is directly proportional to the price of altcoins. So when the price of bitcoin increases expect the prices of altcoin to increase most of the time. Though sometimes there are occurrences where the price of an altcoin increases while the price of bitcoin decreasing. But you are right that it would be difficult for some altcoins to catch-up with bitcoin in terms of its price.