Will AI Replace Software Engineers? What the Data Actually Says

Sixteen senior developers used the best AI coding tools — Cursor, Copilot, Claude — on real tasks at real companies. They finished 19% slower than when they worked without AI. And they were sure the AI had sped them up — by about 20%. The researchers ran the experiment again in February 2026 to settle it, and the experiment itself collapsed: developers refused to do the tasks without the AI. The counterfactual is gone. The experiment to measure if AI helps engineers has lost its control group.Meanwhile, the money is undeniably real. Cursor crossed $2 billion ARR. GitHub Copilot has 4.7 million paying seats. Claude Code reportedly hit $2.5 billion in its first year. Someone is paying, at scale, for something we cannot reliably measure. The wins on bounded tasks are real — Stripe runs 1,300 AI-written merges per week, Rakuten agents tackle problems inside 12.5-million-line codebases. But two-year telemetry across 22,000 developers shows the cost: code churn up 800%, bugs per developer up over 50%, deployments per week DOWN 11.7%. More code, generated faster, shipping slower.The cut is landing entirely on the first rung. Entry-level engineering postings fell 60% from 2022 to 2024. Programmer employment for ages 22 to 25 is down 20%. India's four biggest IT firms added 3,910 net employees over a year — firms that used to hire 10,000 in a single quarter. Amazon's CEO said work that used to take 40 engineers now takes six. Stripe's leadership worries out loud what entry-level looks like in ten years. We're automating the junior work that makes a senior, with no plan for how to make seniors without those years.The optimists have history. Compilers, offshoring, spreadsheets — each was supposed to end jobs, and didn't (there are four times as many accountants now). But three things are new: speed (toy to threat in three years), scope (it replaces ladders, not tasks), and the strangest — we can no longer measure what we're trading.The verdict: no, AI is not replacing software engineers the way the headlines mean. But yes, it's already replacing the on-ramp. The danger was never the robot that codes — it's the missing rung on the ladder. We're sawing it off while flying blind.One bold prediction: before the end of 2026, a big-name company that quietly stopped hiring junior engineers reverses course. The trigger won't be quality — engineering pipelines fail slower than that. It'll be one CFO deciding the math looks wrong, before the damage shows. Sixty percent confidence, not ninety.RELATED EPISODESHow AI Agents Actually Work — same bounded-vs-fuzzy splitThe AI Layoff Gap — macro layoff narrative; here it's the engineering cutWhen AI Agents Go to Court — liability when an AI PR breaks productionThe Loop Closed in the Sandbox — AI doing AI's own work, shipped to every engineerCHAPTERS00:00 19% slower (and they couldn't tell)00:34 A productivity gain nobody can measure01:10 The money is real02:12 The METR study, and why the experiment broke05:15 Maybe we're measuring the wrong thing05:46 Why the code is getting worse08:13 The benchmark scandal08:55 The cut lands on juniors12:21 The pipeline time bomb13:50 What history says — and what's different15:44 Denmark, and the verdict16:33 The bold predictionSOURCESMETR (Jul 2025 + Feb 2026): 19% slower with AI; experiment broke when devs refused to work without itNBER (Feb 2026): 9-in-10 firms report no measurable AI impactGoldman Sachs (Mar 2026): AI ~zero to US GDP; ~30% gain in narrow uses including softwareFaros AI (22,000 devs, 2 yr): churn +800%, bugs +50%, deploys -11.7%SWE-bench Verified ~80% → held-out SWE-bench Pro ~46% (contamination)BLS / Stanford / NY Fed: entry postings -60%, ages 22-25 -20%, CS-grad underemployment >40%Cursor ~$2B ARR, Copilot 4.7M seats, Claude Code ~$2.5B ARR (single-source)Org cases: Shopify, Amazon 40→6 (Jassy 2025), Stripe 1,300/wk, Klarna rehire, India big-4 +3,910Jevons history; Denmark NBER null; Anthropic CEO forecast