The only way to see the kinds of speed-up companies want from these things, right now, is to do way too little review. I think we're going to see a lot of failures in a lot of sectors where companies set goals for reduced hours on various things they do, based on what they expected from LLM speed-ups, and it will have turned out the only way to hit those goals was by spending way too little time reviewing LLM output.
They're torn between "we want to fire 80% of you" and "... but if we don't give up quality/reliability, LLMs only save a little time, not a ton, so we can only fire like 5% of you max".
(It's the same in writing, these things are only a huge speed-up if it's OK for the output to be low-quality, but good output using LLMs only saves a little time versus writing entirely by-hand—so far, anyway, of course these systems are changing by the day, but this specific limitation has remained true for about four years now, without much improvement)
So will it turn out that actually writing code was never the time sink in the first place?
That has always been my feeling. Once I really understand what I need to implement, the code is the easy part. Sure it takes some time, but it's not the majority. And for me, actually writing the code will often trigger some additional insight or awareness of edge cases that I hadn't considered.
"So will it turn out that actually writing code was never the time sink in the first place?"
Of course it wasn't! Do you think people can envision the right objects to produce all the time? Yeah.. we have a lot of Steve Jobs walking around lol.
As you say, there's 'other stuff' that happens naturally during the production process that add value.
My prediction is a concorde-like incident is going to shatter trust and make people re-think their expectations of the capabilities of LLMs and their abilities of the present.
Essentially something big has to happen that affects the revenue/trust of a large provider of goods, stemming from LLM-use.
They wont go away entirely. But this idea that they can displace engineers at a high-rate will.
Assuming you mean this crash [0], it reads to me more like a confluence of bad events versus a big fundamental design flaw in the THERAC-25 mold.
I feel the current proliferation of LLMs is going to resemble asbestos problem: Cheap miracle thingy, overused in several places, with slow gradual regret and chronic harms/costs. Although I suppose the "undocumented nasty surprise" aspect would depend on adoption of local LLMs. If it's a monthly subscription to cloud-stuff, people are far less-likely to lose track of where the systems are and what they're doing.
[0] https://en.wikipedia.org/wiki/Air_France_Flight_4590
Like bombing a building full of little kids? Oops too late...