Maybe you're right and in several decades BTC may become so appreciated all over the world that people will consider it national treasure. But now I don't see such tendencies.
Bitcoin cannot be a national asset, because its ownership is anonymous. So the amount of bitcoin that is owned by citizens cannot be known. As long as bitcoin is stored in the wallet, no one knows except the owner, so the government cannot claim bicoin as a national asset. The government can find out someone has bitcoin when bitcoin is exchanged into fiat currency.