Put another way, there is nothing fundamental in quantum physics itself that prevents large-scale quantum computers from existing, and we know this from experiment after experiment after experiment, observation after observation after observation. The same way we know that we can build a fusion reactor that works at scale, there is nothing in physics saying no, even though we've never built one before.
It’s an engineering challenge. When we talk about dealing with heat in quantum processing, it’s not in the sense of “bigness” or preventing the system from becoming “accidentally classical” as the number of qubits grows. It’s an old fashioned engineering challenge, basically refrigeration.
The industry is moving away from the big chip model toward a modular, networked approach and and different qubit technologies. So instead of on massive chip requiring thousands of control lines you get many smaller but highly connected QPUs, and this reduces the cooling challenge to something manageable.
Two entangled particles can be separated by the entire universe and still remain entangled. Modularity is not at all anti-quantum, nothing along the path to 2,000 qubits (or however many) is anti-quantum.