BTC is completely unsuitable to be used as a currency, since it's deflationary. Would you buy a car if waiting meant you could have it at half price? Of course not, that'd be stupid. So you'll sit on your hoard, while the economy implodes.
If you mean to say it's not deflationary because there's a limited amount of it that doesn't technically decrease, that doesn't help.
First, Bitcoin does lose coins over time. When wallet keys are lost, or "dust" happens, that means that money can't ever be spent again. This is independent of the USD value.
Second, the economy can grow. Eg, if the population grows, or a factory starts producing more goods, then there's now more stuff per unit of currency. That's still deflation.
However, if everything else is inflationary then simply not inflating would be deflationary on a relative scale. It is a near zero chance that countries don’t keep inflation strong.
