I think there are two huge problems concerning the Bitcoins future use in daily life.
1) Slow transactions
Its a turtle compared to most of the other coins, why should we choose Bitcoin? We actually need real time payments (as we already have them in real life)
2) No reimbursements
Paying using Bitcoin (or other cryptocurrencies) can be really really stressful.
If I make mistakes in sending bitcoin (and people make mistakes all the time) I wont never get reimbursed in any way
its not the same with FIAT.
If someone clones my credit card I have some chances to get my money back
what about bitcoin?!
At the moment, its impossible that Bitcoin or other cryptos are going to replace FIAT money in every days use.
Moreover, some more modern currencies have a better technology.
If we really will use cryptocurrencies in daily life, why should Bitcoin be the best coin to use?
This is the key question, because if we wont use it, Bitcoin will be worth 0 and not 100.000$ as someone says.
All of your questions have been answered and i have the same exact answer to them. As to the key question you're asking, there's no way bitcoin will have no worth at all in the future. Some also say that bitcoin is like gold which the will never void in value