Opus 4.6's coding ability is nowhere near as good as Opus 5.5's. Some model next year will almost certainly be significantly better at coding (and planning, and designing, and ideating) than Opus 5.5.
You're narrowly focused on writing code. What about when they can run entire firms themselves, better than the average human CEO could? What about when we have models way, way, way better than Opus 4.6 and 5.5?
The point is we will eventually very likely have AI systems that can do everything. Everything. Anything and everything a human can do with - or even without - a computer, and then better than anything or everything a human can do, including in terms of creativity and innovation and novelty and insight. Obviously I don't know when that might possibly be, and it's not happening next year or something, but you can't just pretend like we hit the cap on the technology.