Well, after seeing this gen we can't be sure of how much sony would think about eating costs to make powerfull HW... but counting me in on having the best piece of HW for a good price.

No.

Have I become that predictable? :P

Well. GDDR5X can hit 16Gbps anyway.
https://www.anandtech.com/show/11543/micron-discusses-gddr5x-gddr6-and-gddr5

So over time they will obviously be able to push GDDR6 much higher.

It's is the eventual replacement of GDDR5 and GDDR5X, so if scales of economies kick in... Then there is the potential to see GDDR6 in next gen consoles.
Otherwise GDDR5X will be it.

The other competitor could be HBM3, which could have some big cost reductions (At the expense of performance) to make it more viable in consumer spaces, the way that gets achieved is by kicking the silicon interposer to the curb and vastly simplifying the Ram stack at the expense of performance, but driving up clockrates to compensate.

This Ram isn't being "designed for Volta". It's Ram. - Rather Volta has been designed to take advantage of it.
GDDR6 is the successor to GDDR5, GDDR5X took on some "GDDR6" characteristics as GPU manufacturers needed a middle step between the two technologies due to the demand for more bandwidth economically.

GDDR6 will obviously be relegated to the high-end and trickle down into other markets, happens every time a new GPU memory technology arrives.

Bad comparison. No consumer PC GPU had 8GB of GDDR5 Ram when the Playstation 4 launched.
It wasn't until 2015 when AMD pushed out Hawaii and nVidia pushed out Maxwell that GPU's had 8GB GDDR5 or more, years after the Playstation 4 launched.

Fast forward to today... And even mid-range cheap GPU's like Polaris (RX 480/RX 580) can come packaged with 8GB of GDDR5X memory.

If the Ram is GDDR5/GDDR5X/GDDR6 then there will be lots of smaller chips. Probably 8-16 of them if they are using a power-of-2 memory bus.
If it's HBM then there will just be a couple of chips at most.

Sony opted for 16x 512MB chips in the Playstation 4, each chip had a 16-bit connection to the SoC for a total of 256-bit. Each chip operated at 2.75Ghz to provide 176GB/s of bandwidth.

Later on... Sony cut the amount of chips in half, but doubled their capacity and doubled  the connection to 32-bit so that way they retained the same amount of bandwidth at the same clockrate, this only became viable because the appropriate Ram had became available, it did reduce board complexity and save costs.

Even if next gen retains GDDR5X though, memory clocks are constantly increasing, it wouldn't be overtly difficult to see massive gains in bandwidth and memory capacities for the same price over the base Xbox One and Playstation 4.

Thanks for the quick and good comments on a level that is easy to understand.

Summarizing your comments, there is a possiblity of GDDR6 if cost come down fast enough in 3 years and make the prospects of cost during the gen mean a GDDR6 is possible, but if that doesn't pick up fast enough the X will be it right? How much faster and bigger pool would you guess? 20GB and 4x faster?

I know next to nothing on HBM... considering current trends and the fact we are closer to DDR type memory on cosoles usually, it would be harder to get HBM than DDR?

How feasible or more interesting in cost/performance is bigger chip with higher bit count and clock versus the smaller versions? Keeping same trend we would be looking at perhaps something between 1-4GB per module on how 64 bits or more?

It took a long ass time to move from GDDR5 to this one for modern tech standards...

It's difficult to tell, but the general consensus is that a doubling of capacity and performance for the same costs wouldn't be entirely impossible at a later date, but a more realistic goal is probably 50% gains over GDDR5X in terms of capacity and bandwidth in the shorter term. (As GDDR5X was a middle step.)
The biggest issue with GDDR6 is that it requires more masks which means the big factory's that make the stuff need larger clean rooms and more equipment, so it could take a little longer to ramp up GDDR6 than expected.

Just need to wait and see.

HBM is going to always be more expensive in general I think. So that will always keep it relegated to markets that can afford it, HBM3 just brings those high costs down more.
Still a massively long way away before HBM replaces DDR memory in all markets though.

Well. That depends on what's available, what the price is... There is more to the cost of Ram implementation than the amount of chips or their bus widths.
In general the wider the memory bus or the more chips you have, the more traces you need on the PCB, the more traces on a PCB means potentially more PCB layers.
So you need to have a balance there between the two.

Microsoft for instance didn't reduce the amount of memory chips (But did change the ram chips it was using) between the Xbox One and Xbox One S, both have 16x DDR3 512MB memory chips. DDR3 is cheaper than GDDR5 though.

JEDEC is pushing GDDR6 to top out at 4GB per chip (32Gb, 8 bits in a byte.), 16Gbps. - On a 256bit bus with 16x chips you are looking at 512GB/s of bandwidth with 64GB of capacity, consoles will probably have half that capacity though due to costs.

Indeed.
GDDR5 dropped in 2008 with the Radeon 4870 debut and has stuck around right up until today.
Although AMD and nVidia did boost clock rates, they did increase the bus widths from 256-bit to a massive 512-bit in some instances.

32 GB??? XD holy crap and you expect it to be expensive GDDR memory also, most high end pc's don't even have that much if you compare the normal ram+the video ram, that is a completely unrealistic expectation lol

And most sites are speculating that the release of pcie 4.0 will be short lived and the release of 5.0 could be as early as 2019, pc performance then is set to have quite a considerable leap in terms of transfer speed on data in just two years, im just hoping that when the time comes the infrastructure on motherboards and the cpus being released from that point onwards will be able to handle such data rates, as we may see mid range cards finally offering more or less reliable 60fps at 4k across the board, and perhaps 120+ at 4k on higher end cards (purely speculation of course).

I was very tempted to move to dual 1080ti and a i9 7980XE, but I may backburner the idea a little longer to see how each company develops over the next two years, would be a shame to drop 3+k on an upgrade only for it to be considered mid range less than two years later, though since it's pc that's more or less a given lol

Rememba the PS5 is likely November 2020, exactly ~3 years from now

Things can change a lot. From the time the GDDR5 cards came out, to the launch of PS4 was also ~3 years, and they had only 1-2GB ramz. When the PS4 came out, 2-4GB was commonplace. (PS4 2x)

I think 16GB ramz will be the standard in high end gpus around 2020 (this is the gen after Volta/Navi), but the PS5 will have double the capacity. And it's either gonna be 4x 8GB stackz, or 16 x 2GB modules in clamshell mode like PS4. If not, then at the lowest specs, I'd expect 24GB ramz.

People need to dream bigger lol, when you search for discussions from 2011-2012 on enthusiast gaming forums how much ramz next gen would have, most said 2GB, 4GB to be the absolute maximum.

Considering PS5 could sell close to 100M consoles and that it would mean over 100M chips per year that could help make it goes down in price... like how PS4 "lucked out" with GDDR5 that were expensive, but just on the brink of releasing they could double the memory of the console based on reduction of cost.

But I comprehend the enhanced complication to produce.

With the improvements you expect from GDDR5X then we are more likely to have smaller modules and more quantity then?

About HBM... then considering we know that consoles is always how to have the cheapest as possible to meet need then HBM is quite unlikely when faced with GDDR5X =[

On the layers for more modules... considering PS4 were able to have all those layers and still have small board on budget price, 16 chips of 1 or 2GB of GDDR5X wouldn't be an issue when talking price only. 

Well people put it before to you... PS4 launched with 8GB of GDDR5 while the common place was high end GPU to have less than 3GB but the CPU would get both close to 8GB total... when I say 32GB is because I think only doubling the size compared to PS4 (or 50% against X1X) seems quite small jump. But if we are talking on they deciding to perhaps separate the memories perhaps 16GB (4x PS4) for games on GDDR and 4GB DDR for UI could be likely... But I think Sony will keep unified RAM as that helped them make the development of games easier.

Yep I was one surprised they gone from 512MB (which was already a surprise on PS3 reveal) to 8GB on PS4... and considering PS3 gen survived more than any before and this one doesn't look like will survive less, I think the next one shall also survive a lot as we get closer to need preposterous jump to see a difference in IQ... so I keep my narrative that unless sales plummet for SW this gen will go at least 2020 as you said, maybe even more. And Sony will release PS5 only when they can make a big leap on a 399 console, something like 16-20Tflops on more efficient GPU (gaining that 10x over PS4 and 5x PS4Pro) on a 32GB RAM.

How much is it ?