Network Effect --> Stronger (500k per second in global transfer and growing)
Institutional Acceptance/Capitulation --> MUCH Stronger (See PING Man's comment, Blackrock, Dalio, Druck)
M2 Money Supply and Growth Rate --> Much Stronger
Supply Constraint --> Tighter (just math)

I don't know how anyone could know about it replacing currency. The reasons I never bought earlier was because (a) I didn't understand it and (b) Government has guns and can make things illegal. Both are still possible but:

a) The network effect in terms of wealth transfer mechanism is strong and growing. Much more efficient than the old ways. There is no middle man, has the potential to destroy old payments like MA, V and banks. a2) For example, in Venezuela, Bitcoin would have been awesome to own in place of Bolivar.

b) All you have to know is a password and you can transfer it across borders. Really hard for governments to outlaw it.

Speculation for sure.