Bitcoin has no physical presence. What if we just stop believing in bitcoin.
Physical appearance does not correlate to value. A currency like fiat has physical cash notes, but it doesn't have any intrinsic value besides what is placed on it by the nation's economy and banks, who can always print some more.
Physical presence does not also affect believe, no one needs to hold Bitcoin to understand how the network works, but hypothetically speaking, if everyone did forget about Bitcoin, there would be no trade and as such it would have zero liquidity and lose almost all of its value.
I mean every country has the equivalent of gold to their fiat. Bitcoin has no gold or physical value. Can this ever happen ?
Not every county has the equivalent of gold to fiat, and Bitcoin is a decentralized network, it cannot own gold.
What do you mean by physical value? The world is going digital, not everything would be tangible and that's a good thing.