The PS4 is in the Autumn of it's days. The PS4 is heading into thr "final phase of its life cycle," according to Sony CEO John Kodera. Soon it will be replaced by the next generation of PlayStation. Although maybe not quite as soon as you think.
John Kodera was speaking at Sony Investor Day 2018. So these words weren't aimed towards console owners or media, but investors in terms of long term investment and how Sony planned to keep making a return on that investment. So he doesn't mean the console is ending this year, and in fact with the rest of what he said it seems like Sony is planning on releasing the PS5 around 2020-2021.
This is because he talked about their plan to work towards future growth between now and 2021. It takes investment to develop a new console, and usually there's a little bit of time before it starts selling really well. So it sounds like preparations are being laid for the PS5.
Of course if Sony is releasing a new console then odds are so will Microsoft. After all they've made their release dates closer and closer with each iteration of consoles. The PS2 released in 2000, and the Xbox in 2001. Xbox 360 released in 2005, and the PS3 2006. With the current gen of Xbox One and PS4 both being released in 2013. Both companies compete with each other for the top console spot, and bring a console ahead could definitely give Sony an edge.
Hard to believe its already been five years of what was once touted as next gen consoles. Microsoft hasn't had any word on their next console, but with this news from Don't it's doubtful they're far behind.