I think the concern is mostly around the WF races/raid open times, etc.
I think the actual release date is a little less important. Only really an issue would be if xpac launches, and then say raids don’t open for like 8 weeks, leaving folks with nothing to do.
So for example, an early december release date is not an issue, if they push raid/arena season from opening until first/second week of January. The question is… is that too long of a window with “nothing to do” (since you can cap in a few days).