I appreciate your hype, but I don't see the logic to your conclusion.
Activision-Blizzard is likely non-committal with D4 because they are considering it to be a mobile exclusive (speculation).
https://www.pcgamer.com/rumor-blizza...e-last-minute/
Blizzard denies that Diablo 4 announcement was planned for BlizzCon2018-11-05
One of Kotaku's sources said that Blizzard decided it wasn't ready to commit to the announcement because development is still in a state of flux, and the game may continue to change as it progresses.
The only reason I can think of to prevent an announcement due to "flux" is because the
platform wasn't decided on, or Activision-Blizzard did not want to announce 2 mobile games at once. Think about the careful wording of the quote. Something stopped them from announcing it. Changes shouldn't affect an announcement, as they claim they did.
If it comes out on PC it will likely be because of the severe backlash the company received.
It's questionable whether the PC was the original intended market, IMO. Or even if it still is.
If it comes out on PC, it's going to be rushed and forced, which isn't good.