No. For two reasons, a general reason and a specific reason.

Firstly, quantum computing at scale _might_ be possible in our universe but it might not. One of the spookiest things that might still be true would be a thing called finite non-local hidden state. In this scenario the whole universe has some sort of hidden state, a bit like the seed value of a Minecraft world. Quantum computing in a universe with finite non-local hidden state just weirdly "doesn't work" when you scale it up, because it's basically using the universe's hidden state as magic working storage, and that runs out. Simulation nuts would tell you finite non-local hidden state makes it pretty clear we're in a simulation, but then they would say say that...

Secondly it says "near future". We have every reason to believe there will be serious obstacles to scaling up quantum computing. Somebody else gave the example of Babbage's engine. Just because we can conceive of fusion power generation doesn't mean it's going to happen next week.

Or at all. At the start of the 20th century some mathematicians thought all of mathematics could be formulated as a handful of assumptions plus a huge chain of inference. It was just a matter of writing it out precisely. Surely an inevitability. This project was begun by mathematicians and philosophers and it was going pretty well (proving that 1+1=2 for example) up until this chap Gödel comes along and straight up proves it's impossible with his Incompleteness Theorem, if you can do 1+1=2 then Gödel shows how you can write out effectively the equivalent of "This statement is false" and blow up your whole system.

Our current understanding of Quantum Computing implies Quantum Computing is possible.

So the nice thing about QC research is that we either get shiny new computers to play with, or we learn something new about Quantum Mechanics.

yeah- my response neglected "near future"- i don't believe our current encryption methods are "near" broken. to that end, i was obviously wrong.

but i appreciate you reading between the lines and following up with a great response- i have a lot to Google. :)

So... how come they are selling them?

It's a possibility that it'll be a great threat in the near future. Remember that Babbage's Analytical Engine was designed on paper in 1837, and nothing similar was constructed for over a century.

If it's not the near future, we might move to post-quantum algorithms (or quantum cryptography, a field almost entirely unrelated to classical cryptography which involves carefully moving entangled pairs of particles around) before quantum computers become any good at cryptanalyzing realistically-sized encryption algorithms.

I would argue no... there's nothing inevitable about technology. Doubly so for quantum computing. Others will likely disagree.