They typically release 6.5 and then 6.5 part 2 up to 4 months later, so part 2 would be around the timing you gave for a "6.6". But they are also taking breaks for holidays.

We have the last Fan Fest in January and it can usually be expected fairly soon after that. How long after January depends on them, how long they need to delay it and what they can manage. But the release is unlikely be longer than June or July at most because these are the most common months that expansions have released in.

At least we should have plenty of trailers, action trailers, interviews, and media tour information to distract us from the content gap.

What is quite clear is it should be somewhere in the first half of 2024.