I don't think that 4o will actually be available for free. It seemed like they were quite careful in choosing their words. My guess is 3.5 is free without an account, and accessing 4o requires linking your OpenAI account.
They only mentioned 4o, but they mentioned it explicitly at the start, well before they mentioned one can also tie in to their openAI account, if you have one, at the end of the presentation.
To me that implies 4o by default, but I guess we'll find out.
