Could PlayStation 5 and Xbox Series X be swansong for consoles?

This seems to be the question asked at the release of every new generation. Short answer is no, it won't be the last.

They say the same thing with every new console generation, so probably not.

Also Google's Stadia was a massive flop, so I don't think cloud gaming services are going to take over in the near future. Many places also don't have the infrastructure to support it.

There's a reason most people I know are buying the consoles with disc drives.

The subscriptions -- Game Pass for Microsoft and PlayStation Plus for Sony "are going to completely revolutionise the industry as was the case for films and music," said Leprince.

Playstation Plus is not a streaming subscription service - that would be Playstation Now

Games Industry put it best yet:

https://www.gamesindustry.biz/articles/2020-07-17-cloud-streaming-complement-not-competition-to-next-gen-consoles

"Cloud streaming: COMPLEMENT, not competition, to next-gen consoles - Microsoft's decision to bundle xCloud as part of Games Pass Ultimate is the smartest decision anyone has made in cloud streaming so far"

Cloud streaming being in addition to local gaming is best of both worlds

I don't think that this will be the last iteration of gaming consoles and here's why...

Bandwith caps. In the West, a lot of internet providers will throttle your service down or increase your fees if you go over your bandwith cap. Coupled with a lot of rural areas with low speeds, I don't see consoles going away anytime soon. Plus we're forgetting one major factor... They're profitable.