Ryan said he expects up to four years for the PlayStation 4′s expected life span, which makes sense considering the console’s large install base. The PlayStation 2 had a life span of about 13 years, and developers continued to support it several years after the PlayStation 3 approached its middle age.
“The PS4 community will continue to be incredibly important to us for three or four years,” Ryan said. “Many will transition to PS5, we hope if we do our job well, but tens of millions will still be engaged with the PS4.”
Basically console generations are kinda over as you knew them. You will have these kinds of "phased transitions" as a standard I think for everyone.