According to Marcus Sellars, a video game journalist and self-proclaimed insider PS5 devkit were sent out to third-parties earlier this year. On his Twitter dropped the statement:
"PS5 dev kits went out early this year to third party developers."
He later went on to say it's "not a joke" in response to a follower.
PlayStation 4 launched in November 2013 and there have been some unsubstantiated rumours making the rounds that Sony would debut their next console at this year's E3 in June. Typically with new consoles, early devkits can be sent out to trusted partners way ahead of the actual launch, even if the specs aren't fully locked down by then. If Sellars is to be believed, a PlayStation 5 launch in 2019 is certainly a possibility, something that would mean the generation would last around 6 years, shorter than the previous generation, but not unreasonable by any means.