Alot of people are making the assumption that since Sony isn't appearing for E3 in 2019, it means that they'll instead announce the PS5.
In reality - it's the exact opposite.
Sony isn't appearing at E3 because they're not going to announce the PS5. The gaming media is inconveniently putting Sony in a bad position by hyping up the "imminent PS5". While all of it pure speculation and conjecture, it none the less gets people thinking that the PS5 is coming despite zero evidence or confirmation from Sony. Basically, Sony isn't playing ball with the media and figures it's best to quelch rumors and false media hype by not showing up to E3 at all. Which is the right thing to do because Sony doesn't want the potential negative feedback from the community.
For those of you who think the PS5 is coming regardless; you're wrong. Sony absolutely will not release the PS5 until Death Stranding, Last of Us 2 and Ghost of Tsushima have hit shelves.
The PS5 will come out on Nov. 2020, with the announcement happening in Feb.2020 in a live Press Conference. (For those.of you who are unaware, the PS4 wasn't announced at E3 - it was announced at New York press conference in Feb. 2013. The actual console is what was revealed at E3 2013 along with the retail price)