The Vita had a long shelf life, but not a happy one. It launched in Japan in December 2011, right when phone and tablet gaming were taking off -- Sony was trying to sell people on a dedicated handheld at a time when many could play "good enough" mobile games on devices they already owned. And while there were high-quality titles like Severed, tepid sales led developers to shy away. Things only got worse when you included design complaints (such as a reliance on expensive, proprietary memory cards) and fierce competition from Nintendo.
Sony doesn't appear to be planning a sequel to the Vita. That's no surprising at a time when mobile games are still growing, and competition from the Switch could hurt a new entrant's chances. However, it's not exactly in a rush, either. PS4 sales have usually been strong enough to sustain Sony's fortunes, and the company's future may hinge increasingly on PlayStation Now and other cloud services that aren't tied to a single device. Simply speaking, Sony doesn't have the handheld-shaped hole in its lineup that it did several years ago.