The Game Awards showed that they're fine with revealing them elsewhere as long as it still coincides with the anniversary schedule.
We know the next P25 update will be in February. They seem to happen about every other month. Because P4 Arena has been announced for March, I'm not expecting anything in February. However, the following update should be around April, and I think that would be a good time to announce what's coming next.
Food for thought: 13 Sentinels for Switch is the only other Atlus game that currently has a date, and that's already releasing in April. After that they won't have anything to promote, which is why I expect an announcement around that time, if not earlier. We were in the same situation after SMT5 came out, and within a month they had revealed both 13 Sentinels and P4 Arena.
This doesn't directly answer your question, but I think it should give an idea of what we might be able to expect when it comes to timing.