There have been plenty of rumours that Sony might be scaling back its multi-platform efforts, particularly on PC, for non-multiplayer titles, but judging by a Japanese job listing discovered by Phrasemaker, the situation may be more complicated than that.
In the ad, Sony states that they are working to improve the PlayStation Network, which includes PC, console (so not necessarily just PlayStation), and mobile. They also mention that this work on cross-play is being done to support "hundreds of millions of people," meaning far more than just PlayStation players:
"We are currently working to further improve the communication features that connect players around the world and to develop new features (voice chat features) for distribution across multiple platforms (console, PC, mobile)."
So far, it seems that this concept is still a ways off, and Sony further explains where they stand in the process:
"This project is in the phase of considering and building a new server architecture, without being bound by existing frameworks."
In other words, it will likely be a long time before we see any actual results, and perhaps this is a service that Sony aims to have ready just in time for the launch of the PlayStation 6, which is widely rumoured to be in 2028.