It really all seems to flow together pretty organically, IMO.
On the novel front, WotC is not producing anything at all, they have licensed to Penguin so that Penguin pays to make and market books while WotC collects a percentage, which is precisely what WotC said that they wanted to do with novels when they shut down their in-house fiction line.
Back in the early days of 5E, the WotC team always insisted that they wanted to do Settinfs, but were working to figure out to do it properly, and seems they cracked that with the 1-2 punch of Ravnica and Eberron, with all subsequent Settong products built off of their model to some extent or another.
I do agree that the October book smells like the return of Magic to D&Dz and the big D&D presence at MagicCon in a few weeks might be why the D&D team announce there is an October book yet hasn't said anything about it. It is also interesting note that Magic Sets and plotlines have a 4 year lifespan from conception to publication, which means that the current Magic storyline resetting the Cosmology was having the end planned out in laye 2021...when Strixhreleased for D&D, and the D&D team was working on the outlines for their 2024 rules change. It would have been a good time to plan a big Magic entry to the new rules.