Manufacturing and shipping of the PS Vita will end in 2019 in Japan, Hiroyuki Oda, senior vice president for Sony Interactive Entertainment, told Famitsu at Tokyo Game Show 2018. Oda also added that Sony currently has no plans for a successor to the PS Vita.
Currently, we do not have any plans regarding a new handheld device. In Japan, we will manufacture PlayStation Vita until 2019. From there, shipping will end.
Earlier this year, Sony announced that it would be ceasing production of physical Vita games, and that PS Vita games would no longer be part of the PlayStation Plus monthly lineup after March 2019, which pretty much pointed out that Sony was giving up on the system. Oda's statement at Tokyo Game Show 2018 is just the final nail in the coffin for a handheld system that never achieved its full potential.
It's currently unknown when will production cease outside of Japan, but it's clear that it won't much longer till it happens.