How AI Agents Are Replacing SaaS: The Next Big Shift in Software (2026 Guide)

The SaaS market hit $315.68B in 2025 ( Fortune Business Insights, 2025). That’s an industry built on selling access to software seat by seat, feature by feature, subscription by subscription. But something is shifting underneath it. AI agents don’t wait for you to click a button. They plan, act, and iterate on your behalf. That changes the fundamental value proposition of buying software. This post breaks down exactly what AI agents are, where they outperform traditional SaaS, which product categories face the most pressure, and how to think about your own stack in 2026.