You are definitely not seeing this from the bigger picture. Digital currency is basically a threat to the old conventional paper money, as the world is heading toward the cashless society then paper money will surely feels its effect. The world doesnt really need the old conventional paper money anymore because there are alot of cashless form of payment and someday it will be taking its toll towards paper money
It's more then a thread but it will be something that's here for decades. Remember so many people don't even now what online banking is.
Even in western countries. So the future for paper money is that it will be used. Not more, not less.
Yes, it will be always survive, as majority of people don't want to get on online stuff, they find using paper money easy and convenient, they will never complicate their spendings by getting into crypto.