Then the gap here is probably from you applying logic from other areas, assuming its a one size fits all logic.
You sounded very sure that they won't announce a successor until 1~2 months before launch, but I can't think of a single console successor which was released just 1 or 2 months after announcement like you proposed. Even the Switch Lite was a little more than that. Which means your opinion hasn't been aligned with whoever has been in charge of marketing on Nintendo, Playstation or XBox so far.
Maybe they hired idiots or maybe, just maybe, they're accounting unique characteristics of the console market you aren't. For example:
- Main profit streams are heavily dependents for years of a single product success
- If that product fails, it's really hard and costly to salvage or replace it in a short time
- Someone buying a successor is highly preferred over the current product because software support (and thus software sales) will heavily decline after a couple years for the later.