Things change radically month to month. Nobody is remotely close to capturing the market or having any kind of stability over time. People move around quite a lot, often to sidegrade within a generation. Just playing fly on the wall with discourse would be enough to tell you all of this, even without the data to back it up.
Also, OpenRouter misses most of the usage of the US models, as most people are getting those from the vendor directly via subscriptions.
You can argue there's a selection bias that openrouter users are less likely to display model loyalty, but it would still be a visible confounding factor if it was a statistically significant behavior. And it's not. Nor is there a visibly meaningful indication that people don't sidegrade between models. With every single data set, you're going to see that. You're also going to see it reflected in discourse, as I mentioned. Fact of the matter is there isn't a status quo in AI any more than there's a status quo in cars.