So, 3 out of the 4 that they've confirmed to be there, are 2019 titles, right?
That's excluding Days Gone, Dreams (whatever happened to this?), the Bluepoint Games rumored HD Remaster "on a big scale" (high chance of Demon's Souls) and of course, Shadows Die Twice. 2019's gonna be pretty lit for them to even care for more first party announcements at this point in time. There's also timed 3rd party IP's like FFVII:R, Shenmue III (and maybe DMCV & REMake 2, if they get announced here or TGS and end up being timed on PS4).
They can even spread some of those first party to the 1st half of 2020, and then launch the PS5 in November, just like they did with God of War: Ascension and The Last of Us in Q1 and Q2 of 2013 and launch the PS4 in Q4 2013.
Maybe Days Gone (Q1 2019) Death Stranding (Q2 2019), and Dreams in 2019 (Q3 2019), with Demon's Souls Remastered (Q1 2020), Shadows Die Twice (Q2 2020), The Last of Us Part II (Q3, or even Q2 2020, like the first game) and then build hype/momentum onto the launch of PS5 in November 2020? Sounds like a plan.
A month left for E3, huh? Time flies indeed...