No....

16GB of GDDR6 with 256-bit bus = 576GB/s.

24GB of GDDR6 with 384-bit bus = 864GB/s 

I can't say anything about what GDDR6 on a 512-bit bus would reach but instead I ask this. At 864GB/s we are looking at bandwidth more than 4 times whats in the PS4 today. You really think we need that much bandwidth in a console to push 4k games? I doubt. HBM would be great... but its just not necessary.

Well. GDDR5X protocol and interface training sequence are similar to those of the GDDR5, but adopts the 16n prefetch that GDDR6 is adopting.
We could say it is an extension of GDDR5 rather than something new, the name of the DRAM backs that up.

It mostly existed because GDDR6 was so late to the table, we needed an interim solution.

I'm just going to take a wait-and-see approach on GDDR7, if we get it before 2020 then great.

GDDR6 is cheaper though for it's given capacity, which is why it will be leveraged for next-gen.
Unless GDDR7 is ramped up before then, but I have my doubts.

With that in mind... If AMD drives home the memory controller, I am sure they could push the bandwidth, AMD and nVidia pushed GDDR5 to it's absolute limits, power consumption be damned even.

Even after using Samsung's 18 Gbps GDDR6 modules, it still won't hold a candle to HBM 2 ... 

We don't need 4K for next generation, we need something far more and that physically based dynamic global illumination ... 

If we can't get GDDR7 then hopefully they make do with just GDDR6X by just doubling the bandwidth and not touching the densities. I'd be content with just 16GB with 4 GB of DDR5 dedicated to the whole background ... 

8 Zen 3+ cores (with AVX-512 + TSX), successor to Navi microachitecture and at least 1 TB/s (wanted 2 TB/s) for PS5 should be the baseline ... (next generation could be our last one) 

800GB/s to 1200GB/s isnt that bad when the speeds are that high. I am not saying GDDR6 is better than HBM, we all would love HBM.... I am just saying it may not be feasible for consoles. Primarily due to its  Costs and complexity of design.

And I feel we are going to get 16 to 20GB of GDDR6... most likely with a 384-bit to 512-bit bus dedicated for the games and also 8GB of LPDDR4 ram dedicated for the OS. Well, 6 or 8GB of LPDDR4. LPDDR4 is more than adequate for a console OS.

It's pretty bad, we're probably going to have to deal with reconstructed 1080p like Killzone: Shadow Fall multiplayer to get a leap in next gen visuals ... 

HBM won't be feasible for next gen consoles by then ? HBM technology when it first hit the market (AMD Fiji) will be 5 years old by then if next gen consoles release in 2020 and 6 years old if they release in 2021 ... 

No more than 4GB for the console OS is fine and I'd prefer it if we also stick with DDR5 since LPDDR4 will be dated and not have much of future in terms of volume production while DDR5 will be produced for many years to come ... 

I think you are underselling the value of GDDR6 and over estimating the needs of bandwidth in games next gen. 800GB/s is more than enough for next gen games. And sure as hell is a far cry from bandwidth saving checkerboard rendering techniques. 

Secondly, while HBM as a tech will be 5yrs old by 2020, that has nothing to do with the maturity of the tech. Eg the electric car has been there before ice cars were made but are only mature enough today over 100yrs later for the mass market. Same applies here. HMB or even HBM2 may be well known technology by 2020, that doesn't in any way mean it's ready to be mass-produced to the tune of 30M packages reliably every year for both the PS5/XB2. Hell even Samsung is hedging their bets with regards to the tech as opposed to doubling down on it completely .

As with LPDDR4, it really doesn't matter if it's dated by then. you won't be seeing that age of your ram on the home screen. What's important is it's price, performance and ease of use. And you do realize that LPDDR4 is basically smartphone memory right? That's what you see in phones. So basically I'm saying the ram used in the next gen console for the OS will be a smartphone memory solution. Cheaper. Uses less power. Smaller form factor and less complicated. If LPDDR4 isn't being used by the smartphone industry by 2020... Then it would be whatever replacement they are using that I expect to power the OS of the PS5. Unless you feel smartphone memory bandwidth is too low to stream Netflix and YouTube and manage some system operations.

@Bold No, bandwidth is going to become a massive bottleneck in the coming years and graphics programmers will have to rethink optimizations on the algorithmic side. Base PS4 has a flops/byte ratio of 10.4 while it it is nearly doubled on PS4 Pro with 18.9 flops/byte ratio while RX Vega 64 is pegged at an alarming 26.2 ratio. 800 GB/s is hardly enough for next generation and Sony (not just them but the whole industry) will definitely need checkerboard rendering to amplify the low bandwidth deficit ... 

The problem with LPDDR4 is that it's gong to go out of production by mainstream memory module manufacturers before next gen consoles launch so I'd prefer if we adopted the latest standard instead and if we want lower power consumption out of DDR5 we can just clock it lower ... 

You do.

Just for comparision's sake RX Vega has less than 500GB/s even in the liquid version which clocks in at 13.7 TFlops which by 7nm will be about the maximum a console can reach before getting too expensive even by 2020-2021.

What you failed to see possibly is that in the last couple years several techniques had been developed to limit the bandwidth consumption of GPUs, with low-level programming further toning it down (less drawcalls and unnecessary transfers). Without those the Switch would be choked by it's bandwidth, as would Smart devices and APUs. And GPUs also, because then we would already need more than 1TB/s in Bandwidth in high-end GPU

4k TV adoption is happenning a lot faster, and not even because people want one, but because manufacturers arent even making 1080p sets most times anymore. So if you are buying a 55" tv today, you are kinda getting a 4k set by default. Secondly, consoles have to be future proofed. 

And as i have said before.... as long as the PS5/XB2 is made with chips on a 7nm process (as opposed to the 14nm in the PS4pro/XB1x) having at least double the GPU is a given. So the minimum to expect from the next gen consoles is a 12TF GPU. And no one should expect to see the next gen consoles until whenever 7nm chips start hitting the market. If that doesn't happen till 2021; we won't see the consoles till 2021/2022....

I also feel we could have an even far better GPU in these consoles if they go with a split architecture... and I have lots of reasons to believe this is what will happen. Especially with the PS5. To put it in perspective APU in PS4 with a 20CU GPU cost around $130. About the same or hell say $150 for a APU with 40CU in the PS4pro on a smaller node fab process. A split system with a $40 CPU and a $140 GPU on a 7nm fab process will probably have a GPU with at least 130CU pushing around 16-18TF

4K adoption is happening, yet caring for 4K content, not so much. I prefer playing SotC at 60fps, 1080p60 with HDR is fantastic, couldn't care less about it not being in 4K. I play GT Sport in 4K or on my old 1080p tv, the only difference I see is when I look at the far background on some of the tracks. 99% of the time, it doesn't matter. HDR makes the difference.

I really hope next gen will target 1080p60 with improved lighting to make the most out of HDR. Yet I'm sure next gen will all be about native 4K.