Just in case the initial tease, and subsequent Twitter account banner change didn't give you enough of a hint, Counter-Strike 2 has indeed arrived on Wednesday, September 27.
As was always the plan, the game replaced Counter-Strike: Global Offensive on Steam. In fact, the Steam store page retains pretty much everything from the original CS:GO page - reviews, details, release date etc., except it now carries the new name.
This is why it's hard to judge Counter-Strike 2's popularity compared to CS:GO, but what's immediately clear is that regardless of what it's called, Counter-Strike is the most played game on Steam. At the time of this writing, the game has 1,192,773 concurrent players online.