Judging by a recent patent from Sony for 'Ultra High-Speed Low-Latency Network Storage', it seems like they are currently preparing to add PlayStation 5 games to their subscription service PlayStation Now. The patent is bout using multiple NVME drives (which is what PlayStation 5 comes equipped with) for streaming of video games, and also shares a lot of the techniques used for faster access with the actual console.
While most patents are never used, it does seem to indicate that Sony is in fact considering adding PlayStation 5 titles for PlayStation Now. It would also make it possible to play PlayStation 5 titles streamed on a PlayStation 4 or a PC (which currently are the available formats for Sony's game streaming service).
Thanks DualShockers