When talking specifically about scalable quantum computers, i.e. conquering the
error threshold, it’s probably safe to say that they're physically impossible to build in any practical sense. It’s like how nuclear fusion is always 30 years away. It’s theoretically possible but every answer provides 100 more questions. Maybe they’ll be another 50 major breakthroughs but who knows? I doubt it, Patrick certainly has no idea what he’s talking about.
You will probably know better than me, as I know enough to admit I know nothing - but as far as I know, the only examples of quantum computing are incredibly expensive, incredibly unstable and practically unusable - and are just research / theoretical builds?