I think an analogy would be, imagine you are driving across north america in a car, but your engine is broken. The mechanic is near by so you put it in neutral and push it.

If someone said, well it took you half an hour to push it to the mechanic, it will take the rest of your life to get it across north america - that would be the wrong take away. If the mechanic actually fixes the engine, you'll go quite fast quite quickly. On the other hand maybe its just broke and can't be fixed. Either way how fast you can push it has no bearing on how fast the mechanic can fix it or how fast it will work after its fixed.

Maybe people will figure out quantum computers maybe they won't, but the timeline of "factoring" 15 is pretty unrelated.

In the context of cryptography, keep in mind its hard to change algorithms and cryptographers have to plan for the future. They are interested in questions like: is there a > 1% change that a quantum computer will break real crypto in the next 15 years. I think the vibe has shifted to that sounding plausible. Doesn't necessarily mean it will happen, its just become prudent to plan for that eventuality, and now is when you would have to start.

https://bas.westerbaan.name/notes/2026/04/02/factoring.html

It doesn't say much by itself, but it has four very good links on the subject. One of these has a picture of the smallest known factor-21 circuit, which is vastly larger than that of the factor-15 circuit, and comparable to much larger numbers. Another is Scott Aaronson's article making the analogy of asking factoring small numbers as asking for a "small nuclear explosion" - if you're in 1940 and not able to make a small nuclear explosion, that doesn't mean you're much farther away from a big nuclear explosion.

[0] https://algassert.com/post/2500

This assumes that there will not be other problems that arise. I suspect that "error correcting" thousands of qubits entangled with one another will be one of those problems.

To get useful results, a quantum computer needs all of its qbits to stay entangled with each other, until the entire group collapses into the result. With current technology, it is very difficult for a reasonable sized group of qbits to stay coherently entangled, so it can only solve problems that are also relatively easy to solve on classical computers.

If someone today were to figure out how to keep large numbers of bits entangled, then quantum computing would instantly be able to break any encryption that isn't quantum safe. It's not something that we are slowly working toward; it's a breakthrough that we can't predict when, or even if, it will happen.