The way I think about Bitcoin is that it sets the precedence for digital currency, which of course, shifts away from conventional currencies.
It may not be BTC itself to act as a currency that the globe can use daily due to its limited supply and not being enough to go around, but something based on blockchain technology might be more likely.
I don't feel qualified to comment on which current alts this might be as I think we don't have the scalability required on any of the existing coins/chains, but definitely this momentum will trickle into a major digital currency adoption.
Looking at how bitcoin is getting higher and higher adoption every single year, I would doubt that it would be something other than bitcoin that takes the digital currency crown and dethrown the fiat currencies, which is why I think it is quite obvious that we would all be using bitcoin in the future for many things. I am not saying that fiat will be gone, I am sure that will be still available, but instead of being fiat pegged to gold a century ago, we will have bitcoin pegged to dollar in the future and we will all use it.
So, it is not going to be that difficult, it is going to be common and we will definitely live to see it as well it is not going to be too distant in the future. I hope that everyone gets to realize this will be the case before it happens, so that we could profit from it before it happens and get rich.