The concern about quantum computing breaking Bitcoin's security is certainly valid, but as you mentioned, it still seems to be more theoretical than practical at this stage. Shor’s algorithm, which can break traditional encryption like RSA and ECC (used in Bitcoin to generate private keys), could indeed be a nightmare for crypto security. However, the reality is that, at present, quantum computing is far from having the necessary capability to pose an immediate threat. As you pointed out, most quantum computers today are, at best, experimental machines with few qubits and high error rates.

That said, the threat cannot be completely ignored. Technology advances quickly, and the idea of a "quantum supercomputer" capable of breaking Bitcoin’s security in the not-so-distant future is not far-fetched. So, the fundamental question is: how will cryptocurrencies adapt? The answer lies in post-quantum cryptography, which is already being explored by experts. This includes transitioning to new algorithms that would be immune to quantum attacks, such as those based on lattices or other techniques that do not rely on the complexity of prime factorization or discrete logarithms, both of which are vulnerable to quantum computers.

On the other hand, adaptation won’t be simple. The transition to a new security system can be a painful process, and many older wallets could indeed become vulnerable. The update process may cause confusion and even pose risks of failures, with users losing access to their wallets if they don’t migrate in time or securely. This places a huge responsibility on the Bitcoin community to ensure that everyone can adapt without losing their funds.

And if we’re talking about resilience, Bitcoin has been impressive in evolving and adapting over the years, facing various threats and challenges such as forks, 51% attacks, and regulatory issues. Innovation and a strong community may be key to implementing measures that protect the network.

However, we shouldn't fall into the trap of thinking that "nothing will happen until then." It’s important to stay vigilant and start preparing now for a potential transition. While quantum computers are still in their early stages, Bitcoin and other cryptocurrencies must continue developing solutions to ensure that, when this problem becomes real, digital currencies can still operate securely and effectively.

So, is quantum computing a threat? Yes. When will it happen? Maybe not anytime soon, but it’s something the community needs to be aware of. And while the "final boss" of quantum computing is still far off, Bitcoin’s adaptation to it will be crucial for maintaining its security.