I see 10% people worldwide using Bitcoin after 20 years. Just like Silver which was $80/ounce in 1980.
I'm sure that in 20 years there will either be very large transaction volume or no volume -- Satoshi Nakamoto
Bitcoin at $600 will also be valuable and will have long term future. Silver at $17/ounce is a precious metal.
Bitcoin at low costs will also be a very valuable thing but only if it exists in every country or atleast some countries across the world, the way bans are being imposed on bitcoin and other cryptos in some countries across the globe, the situations are really becoming dire, if bitcoin survives this storm of bans then for sure it has a very bright future prospect but if not then I guess it will be pretty hard, although black market for cryptos might surface.