From what i understand the 15 factor was just a stunt and didnt use the actual error corrected algorithm that needs to be used in general.

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.