I myself have my own Altcoin bags that I am holding in perpetuity which I hope that I can dispose of in due time. Some of my holdings are just to embarrassing to even mention to tell that I have them but they are now my investment and hope that in the near future I can sell because right now if I would sell them I will just lose money.
So if is just better to hold them than just accept your losses, after all most of the Altcoin prices in my opinion are correlated to BTC so with that assumption of mine there is still hope that I can still make profit out of my investments.
One of my Altcoin investments is XRP, I had picked that altcoin because of its popularity and the potential that it will go up considering that it had gone up in value of more than .0001 BTC in the past. So it is just fairly easy to expect that in the future it can reach that price point again.
I am also holding a bit of Dogecoin for almost the same reasons so hoping that it will rise up to a hundred Satoshis per Doge is just a fun thing to even thought about. Again I am just assuming that Doge too is correlated to that of the BTC's price. So if BTC would really go higher up in value for the mid-term so will be BTC.
The case and pint here is that most of the major Altcoins will definitely stay because people use them and they are traded with BTC. Meanwhile Bitcoin's value will continue to grow because of the main aspect of a limited and ever-dwindling supply as its scarcity gets to grow as days passes by when new users are acquiring, obtaining BTC in one way or the other to store and sell in the future.
It is a snowball effect which is a tested factor for a cryptocurrency's value to grow because of the law of supply and demand and as users profit from BTC they will again look for their altcoins of their liking to invest in and so the crypto economy is fanned which will mean that we will going to have an ever-invigorated buy and sell crypto market that we can rely upon to earn some money through investing and trading.