A console generation lasts as long as a console generation lasts. If the PS4 would have 1GB of ram it would also last the generation the PS4 is part of duh....

By 'enough to last this gen' i think he means it's enough to not become an issue. Sony and MS underestimated how much RAM they'd need with the PS3 and 360, which resulted in it becoming a bottleneck for many developers in the latter half of last gen.

He focuses on ram, but as others have said, the bottleneck this generation is CPU and to a lesser extent GPU power. We can see from the downgrades of various titles that third party developers had higher expectations for the 8th generation, power-wise. I think both Sony and MS expect this generation to be shorter than the last (5 years vs. 6-7 years) so it shouldn't be a big issue.

Quite possible next gen wont launch until 2019/20. To be honest, the big 3 deserves to make money for all their efforts. And longer generations will make them more money.

the memory isn't really the problem.

the crappy amd cant handle 8 gig, or 4...

With 2/3 consoles not doing that great compared with their predecessors I can't see it happening. It will be much like the sixth -> seventh generation transition. Nintendo will probably release their home form-factor of their next platform either at the end of 2017 or 2018, Microsoft in 2018, and Sony won't want to be left behind so they'll release with Microsoft and/or Nintendo.  

RAM size probably won't be a problem, but RAM speed might.

Of course, after all, the 8GB RAM for both consoles was a pleasant surprise, a 16x increase.

CPU power on the other hand is negligibly better, essentially the same, the only improvement there is that it's simpler to code for.

Cpu's won't be to much of a bottleneck as many hade expected at first. Mantle and DX12 show that even slow cpu's don't have to be a botleneck, definitely not at the level ps4/xbox one's gpu's are at.