Every SaaS category will be rebuilt with AI agents as the primary customer. The next decade creates a market of billions of agent customers with wallets, wanting agent-native versions of every existing tool: payments, communication, memory, project management. This is not a feature layer on existing SaaS -- it is a category-level rebuild where the consumer species changes from human to machine. The strategic question for any SaaS tool is: "What is the version of this built purely for agents?" Agent-native payments (not Stripe with an API), agent-native communication (not Slack with webhooks), agent-native memory (not Notion with integrations). - **Mechanism**: Agents become both primary users and primary customers of software, creating a machine-to-machine economy - **Scale**: Billions of agent customers with autonomous wallets - **Timing**: "Almost nobody is building for it yet" -- first-mover window open - **Cross-Reference**: [[Agent-as-Primary-User Software Redesign Imperative]] (Aaron Levie's six-dimension redesign), [[Agent-First SaaS Design Paradigm]] (API-first insufficient; agent-first required), [[Non-Engineering Agent Deployment Gap]] (most departments under 10% penetration), [[Zapier Complexity Gap as Agent Opportunity]] - **Source**: [[build startups for agents]] (Greg Isenberg, March 2026)