Technically they are a fork, and I believe that they have some manpower to sustain it for a time. I don't believe that they have, or will ever have, the manpower or the know-how to for example rewrite critical parts of it. And so, they completely depend on Google open-sourcing the Chromium project. Should that project be abandoned AND the internet diverge from the current standards, they and other Chromium based projects would struggle to keep up, if even.

So yes, the Brave project is much more than a reskin, or rebrand. They put way too much effort in for that. But the intent of the communication, that Brave absolutely depends on Google, is valid nevertheless.