2020 at the very least is when it makes the most sense as that is when the PC should see enough of a technological advancement to make a generational leap more feasible.

Otherwise you will just get a slightly upgraded Xbox One X.

CPU/GPU process is normally discussed as main factor in new gen launch (which it is), but memory process and data-bus developments could also be factors, although I'm less familiar with announced developments there and their 'due date'...?

interesting. it true the ps4 is selling so strong but isn't a 8 year cycle a bit long especially now a days?

I guess I can see a 2021 at the latest in Nov as usual because of sales.  

But sony did say by 2020 50% of the buying public will have 4k tv's so maybe 2020 they will give us PS5 4k 60fps system. Thats the critical point 50% apparently?

yeah I was thinking of waiting hoping for a 2018 launch. but I might after the poll just grab a bundle Ps4 Pro. I already have an x1 and instead of getting xb1x ill get ps4 pro instead to play the last of us and zero dawn lol. 

I updated the poll cuz it seems people think its gonna be longer! dam!

I look at how many Decembers its been on the market. From December 2013-December 2017 counts for 5 years. That means its specs are from 2011, make the tech 7 years old...... Its time for a new PS no matter what anybody says, the PS4 is old by any reasonable standards.

Nov 2020 is my guess. By that time, a Zen 2/Navi APU should be feasible and be more up-to-date at that point than the PS4's specs when the system released in Nov 2013.

I would go for 2020. why?
1 - PS4 is selling even better than PS2 did.
2 - Software is doing great and has a pile of exclusives almost without competition.
3 - Switch is not diminishing PS4 sales much.
4 - AMD and Nvidia will have 7 nm products ready for 2019. So in 2020 process will be mature.
(AMD 7nm “Super Secret” Navi GPU Spotted In Driver, 2H 2018 Launch Expected.)
That translate in faster processors that consume less power.
5 - 4k TVs will have much larger installed base.
6 - a 2020 PS5 will be fast enough for 30 fps native 4k gaming at high quality graphics settings. (don´t tel me that PS4 pro or XBOX one X are real 4k native systems for every game. They are not.)

2020 The PS4 is doing Terrific, there is no need to release PS5 yet. Considering TLOU2 most probably will release in 2019, I dont think they would announce PS5 and steal the thunder of the game

HBM2, GDDR5X is already mass-market.

GDDR6 is ramping up and will be mass produced this year if it hasn't already. (Couldn't be bothered to check)
So memory tech shouldn't be a hindrance.