This.... Is actually somewhat of a smart move, especially considering Japan.
With the switch out I don't think they have a good shot at maintaining install base if the ps5 was a traditional next gen. But with this Japanese developers would be happy to keep selling on the existing PS4 install base.
Of course, this is a double edged sword, meaning that most JP devs would stay developing at PS4 slim power levels. And at that point, just a bit of optimization and you can make a switch port to sell on it's bigger install base.