When Google announced Gemini 4 Argon on September 30, it used a telling phrase: the first Gemini 4 model. Argon reached Stable GA on October 13 on a new pre-training run, and the rest of the family is now the most predictable open slot on the release calendar.

Why late Q4 fits

Google's flagship cadence is annual and late: Gemini 1 in late 2023, Gemini 2 in late 2024, Gemini 3 in late 2025. Argon's September announcement was early by that rhythm, which leaves a natural late-Q4 slot for the Pro tier that completes the line.

We expect the Pro model to push on deeper reasoning and agentic tooling, with Google Workspace as the showcase integration. That is an expectation built from Google's stated direction, not a leaked spec sheet, our rumor score of 74/100 reflects a strong pattern with no confirmed date.

Counter-signal: Argon's gap to GA was only 13 days. If Pro follows the same pattern, the announcement and the launch may arrive almost together.

Practical guidance: Argon is safe to adopt now (Adopt Now in our Model Guide; the coming Pro tier is a sibling, not a replacement). Teams specifically buying a Pro-tier reasoning model should wait for the announcement before signing anything annual. Everything we are tracking lives in the Gemini 4 Pro roundup.