I think they would just release 26.3 when it’s planned/ready, and just have more of a gap between the 26.3 release and first betas for 26.4 if they needed more time to develop 26.4. They’ve done this before. It’s not like they have to drag their feet on 26.3 to make time to develop 26.4. While it’s true that normally Apple release betas for the next version shortly after public release of the prior version, that is not always the case. They aren’t required to do that. So I really wouldn’t think 26.3 has anything to do with 26.4 development time.
Also, reports seem to indicate 26.4 is dropping mid-February. If that’s the case, then 26.3 RC this week and 26.3 public release next week would make sense and be consistent with those reports. 👍🏻