If you analize the trend over the years you get this great table that took me some time to make.
| Playstation 1 | x | Playstation 2 | x | Playstation 3 | x | Playstation4 | |
| CPU and Video memory | 3 MB | 11 | 32 MB | 16 | 512 MB | 16 | 8192 MB |
| Bandwith | 0,132 GB/s | 24 | 3,2 GB/s | 7 | 22,4 GB/s | 8 | 176 GB/s |
| Gpixels/s | 2,35 | 2 | 4,4 | 6 | 28 | ||
| Gtexels/s | 1,2 | 11 | 13,2 | 4 | 55 | ||
| CPU calculations | 0,066 GIPS | 6,2 Gflops | 35 | 218 Gflops | 0,5 | 102 Gflops | |
| GPU calculations | 192 Gflops | 10 | 1840 Gflops | ||||
| Max Resolution | 640 x 480 | 1280 x 1024 | 1920 x 1080 | 1920 x 1080 | |||
| Optic Media | 0,7 GB | 8,5 GB | 50 GB | 50 GB |
On the topic, next gen should get to 128 GB, but OSs are getting more mobile ready, so I think 32 GB would be my guess in 4-5 year time and 64 GB if next gen comes in 6 to 8 years.
GPU Bandwith increased almost 8 times, so 1,4 TB/s wouldn´t be too far away if stacked memory is arround the corner, coming next year. My guess would be a 1 TB/s bandwith in 6 years.
CPU calculation is less in PS4 than PS3 if you could use all the PS3 resources at once (you cant), Actually the throughput is amost the same from PS3 to PS4. This should be at least 2 times better on PS5.
GPU flops increased 10 times, If it doubles in 3 years now , we can think about a machine that is 4 times as powerfull. New Maxwell and Hawaii cards have 5 Teraflops, more than twice what PS4 has and Maxwell consumes 200W. So its not insane to believe that we can have 8 Teraflops on a 100W envelope in six years
Optic Media is still blue ray. If you need more textures for new games, then you need to get a larger media, at least 2 times what we have now.
So if we have 6 years time for a new PS5 it should be 4 times what a PS4 is now. if PS4 barelly gets to 1080p, PS5 would gets to 4K in six years. because 4K is 4 times full Hd, you need 4 times the flops, bandwith , memory and so on if you want to make it right. And that is considering that you dont change the number of bounces of lights, quality of textures, calculations, and so on.
If they dont do a machine capable of running 4k games, then why would somebody buy a PS5. A lot of people say that there is no much difference in quality between PS3 and PS4 despite the horrible blurry textures that the PS3 has on its very little 256 MB Video memory.
If they dont make at least a 4K capable machine, then nobody would care about a PS5.
We need a Machine 8-16 Teraflops of GPU power, 32 GB of RAM, 512 - 1000 GB/s Bandwith to think about a future gen.
Now, games cost 2 to 4 times more to make in full hd than in SD, I wonder how many AAA companies could afford to make games if they cost 4 times what they do now. Maybe PS5 gen would be hold back from financials and not from hardware standpoint.
