A few weeks ago, multiple gaming sources leaked a handheld from Sony that looks very similar to the Nintendo Switch. The leaked handheld has detachable controllers very much like the Nintendo Switch, and Sony seems to have the same idea that Nintendo had; however, with the success of the PlayStation 4, it would make no sense to release this handheld. Keep in mind that Sony already tried to enter the handheld market with the PSP and PS Vita, which while the PSP did well, the PS Vita was not successful for Sony.
In my opinion, Sony should only focus on the PS4 because of its success. The PlayStation 4 is selling at a faster pace than the PS2, which was Sony’s best selling console of all time. Sony should not waste money on the handheld market for one reason, the handheld market is dying. Smart phones and tablets are taking over the handheld gaming market, and portable consoles are not very likely to succeed in taking the market back. Smartphones and tablets are devices that do everything that a gaming handheld can do and more, and people only want to use one device for portability.