indeed in the world of cryptocurrency all possibilities could happen, but i will still hold my btc as parent of altcoin because i think even though XMR or ETH can surpass BTC, it will not last long.

I think it will not happen, because bitcoin has been set as the parent of all coins, so if other altcoin prices rise, then bitcoin will also increase, because I think brands are mutually mutual. But not also close the possibility that it will happen.

Yes I agree it's impossible for other altcoin to overcome Bitcoin. It's like a tree, Bitcoin is the root and the altcoins are the branches. Without the root the tree will die.

Leave it like that then. So be it. But i don't think Bitcoin's value that time will be too low compared to the coin that surpasses its value and i don't think that i will be selling my bitcoins just to have the more valuable coin in the market. But it will be a good idea to invest that new coin instead rather than selling my bitcoins that i have so I'll be keeping my bitcoins and hold it as long as its value keeps on rising that time.

I consider bitcoin as an investment and if I see another altcoin that would surpass it then maybe I would shift to that coin simply because I would invest to the coin that would be more profitable. Another option is to invest as well to that altcoin not leaving bitcoin totally because it might be just temporary because of a hype. Bitcoin has a strong support from its community that's why it always goes back up because of the demand and if another altcoin would totally surpass bitcoin in terms of demand, price and support then maybe I would invest more to this altcoin.

Well it is interesting to see what is gonna happen ,  however i don't think it will happen.

The upcoming forks must go very wrong to see it happen .

Maybe it will take many years but knowing bitcoin it's so far to happen.
Of course when an altcoin rises, bitcoin will also rise like bitcoin will be never left out to this world.
Bitcoin will always be the best and father of all coins. And thinking bitcoin is too big to defeat by anything not anyone.

Yep, the biggest mistake some holders make is panic selling when Bitcoin goes down. Keeping it for a longer time is the key. It was shown to us many times that however low Bitcoin falls it will recover with time and will rise even more than before. We  can't say the same about other cryptos, although keeping some of them is not a bad idea too. It's just pretty hard to determine which ones exactly.

It would matter little and not be as solid. Bitcoin is the coin that traders buy with FIAT to purchase other coins. That is a big reason for its power. The exchanges only use a few coins as a base for trading and Bitcoin has more access points from FIAT than the others. You cannot get Fiat with any alt unless you convert it in bitcoins. This can be consider on factor of bitcoin domination.