I would be surprised if they made another proprietary mobile gaming device like the PSP/PSV.
If SCE wants to remain in the mobile gaming space, they might be better off licensing the mobile platform or make the platform like iOS or Android in that the operating system, along with the hardware on which it is played on, sees regular (annual for the hardware, firmware/OS as needed) updates to keep in step with current mobile platforms.
The problem with the first is that PSV software development (exclusives from SCE) has all but ground to a halt since it makes little financial sense to pour huge resources into big games for such a small user base, which in turn diminishes the value of the PSP/Vita platform as a commercially viable home for other software titles. At best, it would be a distant third for ports of iOS and Android developed games.
The problem with the second, is that SCE is transitioning out of the mobile market. Ericsson is done, Sony is transitioning out of unprofitable computing devices (Vaio, desktops, etc.) and really doesn't have the strong branding that Samsung or Apple has to create the consumer demand for a regularly updated/upgraded product line.
Consumers who buy a PSV or PS4 expect to be able to keep playing games on them for the next 5+ years on average. Nobody expects that of their current mobile phone which will likely be replaced/upgraded in 2 years.
If SCE released a new PS portable, it's extremely doubtful that anyone but the core Playstation audience would buy one. It would probably be little more than a satellite device for the PS4 (which the PSV has somewhat transitioned into).
Now SCE could feasibly release a Playstation TV Portable device that enables users of that service to take their games on the go, but much like the PSV, there is a limited market for that, particularly if it's a streaming device that requires a data subscription plan for access to LTE/4G data networks. Nobody bought the 3G Vita.
If Sony had a decent position in the cellular/mobile market, the obvious answer would be to incorporate the Playstation brand into those devices, but this would eliminate one of the key distinctive features of the PSP/Vita hardware: the physical controls. At that point, developers really would just be making iOS/Android games that were playable on Sony branded smartphones.







