How long do you predict it will take for the day-to-day volume of crypto assets to surpass that of fiat currencies?
IF the blockchain succeeds, I wouldn't expect to see a potential flippening to happen before 2025-2030. The current level of real world usage for the blockchain is very similar to that of Graphene - "Graphene can do just about anything, except leave the lab".
To use some analogy, Graphene and the Blockchain tech can both do a lot of wonderful things - both are wonder technologies with extremely high potential applications. With both Graphene and Crypto currencies, we know that the underlying potential is huge. However, the challenges are also there. First, you have to come up with a way to use these properties for beneficial applications. Then, you have to scale fast enough while keeping it low cost, which so far hasn't been the case for most cryptos including bitcoin(tx fees,scaling issues) or graphene(high costs for large scale productions).
Even though none of us currently use crypto for day-to-day purchases, the market cap is very high - which is all due to pure speculation, or what I would call, emerging market value. It’s the market that determines ubiquity or obscurity of technology, and it does not care how a technology works; it cares about what problems that technology solves.
If the blockchain tech succeeds in solving the issues facing fiat currencies both physical and digital, one thing is certain. The market cap will grow hundredfold, and it's going to imitate the stock market as a device for transferring money from the impatient to the patient. So HODL
I think it'll be lmat impossible to see Bitcoin surpass the daily fiat volume across all the different daily payment mediums that exist. PayPal alone dwarfs Bitcoin and I don't think that, without substantial growth, that the Bitcoin community will be able to grow past that. You also need to have a vibrant economy that can encourage the transactions, and Bitcoin is currently limited in that respect. It used to be pretty big before with big-box retailers accepting Bitcoin, but it has shrunk somewhat. A lot of the transactions come from casino users and smaller shops to my knowledge. If Amazon-lites like Newegg and Overstock rekindle their interest in Bitcoin, we could see a daily volume flip in the future, but there is still a ton of growth to go through. 2025-2030 may be too early to see that growth occur.