This. I'd personally bet on a Q1 2020 official teaser, at CES, GDC or at an event made in February just for this. The more time they give devs to work on the initial demos and games shown there, and the more time they give to the engineers to work on the specs, the better.PSX 2019/Early 2020 official teaser.
E3 2020 Reveal.
November 2020 release.
In addition to this, if PS5 announcement somewhat affects PS4 sales they may want to wait as much as possible to announce it, specially if as I think PS4 continues on fire with its sales due the huge amount of great/big seller games announced to be released in PS4 during 2019.
Sony said they'll skil E3 2019, very likely because at this point they won't have any big announcement to make. Most remaining big PS4 exclusive games have been shown one or twice so wouldn't make sense to show them again at E3. This pretty much confirms that PS5 won't be released during 2019 because if it was the case they would be at E3 2019 showing it.Sony is skipping E3 this year. Which kind of shows that PS5 at minimum will be announced this year and my bet it holiday 2019 release.
Sony said they'll skip E3 2019, not E3 2020. So Sony can come back to E3 in 2020 to showcase PS5 and its first games.