So you see the PS4 doing about 105m+ by the end of 2019.... I can agree with that (might be higher).

Also I think PS5 doesnt launch until 2020.

Early 2019? That's only a year and a half away from now. That seems too soon.

But PS4 is still selling great, that want change in less than 1.5 year.

Tag. I will write later why I don’t agree and why I think that releasing ps5 earlier than 2020 would be a disaster to Sony.

No. Now that Microsoft beefed up the XBox One X...this gives Sony all the reason in the world to stall so the best parts available can drop in price. 2020 is when it will drop for sure. MS just made that a definite yes. Sony generally replaces their consoles after six to seven years but much like last gen its looking like seven.

I think the PS4 will sell 108-112 mil lifetime. I have a sneaking suspicion that once it hits 2019 most of its demographic will be covered

2020 after seems more right, I expect the focus will be less on the hardware but the new services they will bring...Some PSnow/Psplus integration etc.

Not a chance. You're not going to see next-gen consoles until at least 2020. They'll do the same strategy that they've been doing for their consoles. PS event where PS5 gets revealed in Feb 2020, game/system showcase at E3 and finally release in late 2020.

The reasons for that, even excluding how well PS4 is doing right now, are mostly down to hardware. They simply cannot make a system during that time that will not only provide a significant jump over the PS4 (in terms of everything i.e RAM, storage, GPU, CPU etc) without charging premium price for it, and absolutely nothing suggests that Sony will be taking that route since it's done them so well this generation. As for MS, I hope they take the Sony route in terms of pricing, obviously the Xbox One X is an exception and the original Xbox One was priced higher than competition because of their focus on multimedia and inclusion of Kinect. Hopefully their next base console will be a competent one.

AMD just had their CPU roadmap leaked a few days ago and it mostly confirmed everyone's suspicions, Zen APUs starting in early 2018, one revision of the same architecture somewhere around 2019 and Zen 2 APUs in late 2019/2020. The longer they wait the better, especially since the mid-gen refreshes mitigated the long console gens that everyone hates, now they can relax and think their strategy through.

Early 2019? Nah, holidays 2019 would make more sense.
But my prediction is still holidays 2020.

Sony didn't force Microsofts hand at all. They had a "scorpio" to release in 2016 but decided against it.
https://www.vg247.com/2017/04/12/xbox-scorpio-couldve-released-in-2016-but-microsoft-didnt-want-to-forsake-framerate-for-4k/

If anything, the pro seems rushed in comparison to the X. Sony releasing the ps5 early 2019 will likely play into Microsoft's hands giving them a head start. The console won't be powerful enough to push Xbox one X in terms of a generational leap. Xbox would be the entry level console, running the same games at a fraction of the cost. Though, the ps5 versions would run better. It would be little over a year from one release to the next.

There won't be a ps5 or Xbox infinite until 2020.