I agree with this. I think Sony is putting all bets on the PS5, which seems like the smart move to make given their position. I feel like we've been speculating about the PS5 since the Switch launch, and maybe earlier, and still no info on specs or release date (afaik). They must have something big up their sleeves.
I fully expect a 2020 release, and game development has migrated to the ps5, which is why the ps4 has cooled off this year. And I am fine with that. The ps4 was amazing and worth every penny.