This is the third article in Arion Research's "Future Enterprise" series. Every major enterprise vendor now has an AI agent strategy, but the approaches diverge sharply. Some vendors are embedding agents deep inside their applications, giving them direct access to data models, business rules, and transaction logic. Others are building horizontal platforms where agents orchestrate across multiple applications from the outside. Each approach has structural advantages, and real limitations. This article examines the depth-breadth trade-off, explores where each model wins, and makes the case for a third path that combines native depth with open interoperability.