For frontier AI facilities I’m seeing new training halls and premium AI suites become liquid‑ready by default around 2028; liquid shifts to the default design assumption for new high‑density racks above 50‑100 kW by roughly 2030; and it turns effectively mandatory at hundreds of kilowatts to megawatt rack envelopes by ~2035, when an air‑only AI factory becomes a niche exception. Meanwhile, for general enterprise, storage and networking, air cooling stays dominant and viable for years – the installed base is about 75 % perimeter air‑cooled today, with direct liquid at roughly 22 %.