It is my understanding that bitcoin wallets are created through a hash table with 64 bits of alphanumeric characters. What happens when all wallets are completely used up? What happens then? Just a curiosity question.
In all likelihood the universe will have ended thousands billions of years before anyone (or any group) could generate them all.
And if they did in some alternate reality with different laws of physics, they'd just be reused.
If it ever looked like it was a physical possibility, doubling the length would change that.