I voted for the option that they will both be used in parallel. I voted this way because first and foremost, Bitcoin and cryptocurrency in general are here to stay. That's definitely happening. But because the current way Bitcoin is obtained and transacted, it is too difficult for the average person to use on a day to day basis. The masses won't adopt Bitcoin. Not gonna happen unless there are no fees involved in transacting with Bitcoin, the way BTC is obtained gets way easier, ie. no KYC/AML and that's not gonna happen anytime soon and lastly how long transactions take to confirm or post to signal completion of said transaction. There are a slue of other reasons why your average person will not accept transacting with BTC over fiat for their average everyday lives. BTC is nowhere near ready to even begin to talk about it taking over fiat currency for the average everyday user. To even consider that it is, is just flat out wrong. It may never be ready. There will be digital cash for years to come, but how will it look in the future is up to the needs of the market(s) it serves.