This is what I call future planning. While we're still waiting to learn the technical details and even the appearance of the future PS5, Sony seems to want to cover its bases for the future. And when it comes to patents and registered trademarks, you can never be too careful, so what has the company done?
From PS6 to PS10

With the aim of securing ownership of such iconic brands as PS6, PS7, PS8, PS9, and PS10, Sony has decided to trademark the names of the next five generations of its console to avoid future issues should it release a version with those names. This doesn't guarantee that the brand will continue using those names for its next console, or even that it will release a console at all, but having them reserved will save it a lot of trouble down the road.
Are video consoles dead?

With the launch of the next streaming services that are yet to come, such as Google Stadia or Project xCloud, many pointed out that the physical hardware of the consoles would have its days numbered. But the truth is that there is still a lot to see, try and demonstrate. Streaming services need to ensure that there will be no waiting time between the controller press and the in-game response, and for that there is probably still a long way to go.
In the meantime, actions like Sony's with its new trademarks only make us think that consoles still have a long way to go, however, we agree that they will probably change the way we interact with them, either with greater prominence of virtual reality, more cohesion with social networks or simply evolve to the miniaturization of hardware.
As Gematsu correctly points out, Sony registered the PS4 and PS5 trademarks in 2006, the same year the company launched its beloved PlayStation 3. As you can see, trademark registrations are done well in advance, so it's normal to see these kinds of reservations aimed at ensuring a smooth future. Just consider that they registered the PS5 trademark 14 years early…