Doesn’t have to be Bitcoin, and, I assume, Buffet doesn’t mean it either explicitly. Often Bitcoin in many contexts in understood as a synonym of this new digital money.

Power law/positive feedback/winner take all dynamics make it likely there will be one or a few dominant ones and a lot of would-be's. Bitcoin has maintained the first mover advantage as well as the strongest engineering community thus far, so it will likely be one of those.

The whole transaction can happen in a matter of hours tho. Bitcoin isn't that volatile. And you have to realize that is a means where there was previously none. Like it's not like the people doing this might have that many options.

That being said, I've also heard of western companies using Bitcoin to transfer money cause it's cheaper than via bank.