Unless they can’t guarantee the iPhones sometime in October, I don’t see why the wouldn’t announce all at one time. Wasn’t the X announced in October and released first week of November? Think XR was announced in September and released in late October. Pretty sure they won’t be announced due to the Event Title, but delays have been announced ahead of time before.
You make a good point. But there have been falls with two events before, when there was a lot to announce, and it looks like delays and product cycles have led to a lot of new hardware ready/close to ready, so two events might be the better alternative to a massive 3.5-hour event where some products get buried by those highlighted in the press.