Still seeing "no way the PS5 hits in 2019, cause the PS4 is doing good and new game releases" comments. I'm going to repost a section of a past post.
3rd party PS1 releases in 2000, the year the PS2 launched - Vagrant Story, NFS: Porche Unleashed, The Misadventures of Tron Bonne (Mega Man Legends spinoff), MK:SF, Threads of Fate, Strider 2, Chrono Cross, DQ VII, Spider-Man, TH's Pro Skater 2, Vampire Hunter D, Destruction Derby Raw, Donald Duck: GQ, Mega Man Legends 2, Capcom vs SNK: M 2000, Incredible Crisis, The World Is Not Enough, FFIX, The Emperor's New Groove, TR Chronicles, 007 Racing, Batman Beyond: ROTJ, Harvest Moon, Disney's Aladdin: NR, Evil Dead: HTTK,
Sony PS1 releases in 2000 - Wild Arms 2, Spyro: YOTD, Crash Bash
The PS1 also sold ~21M in 1999, the year before the PS2 launched.
Notable 3rd party PS2 releases in 2005, the year the PS3 was originally going to launch, and 2006 - Mercenaries: POD, Shadow of Rome, Xenosaga Ep II, FIFA Street, Tekken 5, Fight Night Rnd 2, DMC 3, MX vs ATV Unleashed, Timesplitters: FP, Dynasty Warriors 5, Splinter Cell: CT, Lego SW, Midnight Club 3, Psychonauts, Burnout Revenge, MK:SM, Indigo Prophecy, RE4, Soul Calibur 3, COD 2, SW Battlefront 2, Guitar Hero, NFS: MW, DQ VIII, Drakengard 2, MGS3: S, FFXII, KH 2, TR: Legends, Jaws Unleashed, Hitman: BM, DOC: FFVII, Disgaea 2, Xenosaga Ep III, Lego SW 2, Okami, Just Cause, Scarface, MK:A, Spyro: ANB, Bully, NFS:C, COD 3, Guitar Hero 2, TH Project 8
Sony PS2 releases in 2005 and 2006 - The Getaway: BM, MLB 2006, GOW, Rise of Kasai, Genji: DOTS, Sly 3, SOCOM 3, Jak X:CR, SOTC, Ratchet: Deadlocked, Ape Escape 3, Siren 2, MLB 06, SOCOM: CA, Ape Escape: MM
The PS2 also sold ~20M in 2005, the year before the PS3 launched.
Notable 3rd party PS3 releases in 2013, the year the PS4 launched - DmC, Ni no Kuni, Dead Space 3, Crysis 3, MG Rising, TR, Bioshock: I, Injustice, Dragon's Dogma: DA, Metro: LL, Grid 2, Deadpool, Dynasty Warriors 8, Dragon's Crown, Saint's Row IV, Splinter Cell: BL, FF XIV, Diablo 3, Rayman Legends, GTA V, Disgaea D2, Lego Marvel, Batman: AO, AC IV: BF, BF4, COD: Ghosts, XCOM, NFS: Rivals, Minecraft, TWD: S2
Sony PS3 releases in 2013 - Sly Cooper: TIT, MLB 13, GOW: A, TLOU, Puppeteer, Rain, Beyond: TS, R&C: ITN, GT6
Now, the sales argument doesn't quite work for PS3, as sales were starting to decline due to the length of the gen. Though, using VGC's estimated sell-through of 13M+, we can guess shipments were still a respectable ~15M in 2012.
The point is, neither of those factors mean anything when it comes to when a console's predecessor will launch. When an affordable chipset is developed/available that gives a generational jump, they will jump on it as soon as possible. Sony usually waits 5-6 years before jumping, which 2019 would be 6 years. They also have been working with Ryzen CPUs, which is obviously going into the PS5, definitely a generational leap. And rumor has it Navi has been co-developed with, or at least made to meet requirements from, Sony. Meaning that is what the PS5 will have. Now, it will be possible that things don't go perfectly as planned and Sony has to wait until 2020 to launch. However, I think if things actually do go according to plan, we will see a PS5 in late 2019. They definitely want to strike while they are hot, while not giving MS a possible year headstart.