This site most likely read the Andrew House press release wrong. They mentioned that "PlayStation 4...... is set to reach cumulative sale of 78 million units this fisical year". Someone not in the know, and not reading the statment fully could get confused. Fisical Years end at different times for different companys as well, and I would guess most people don't know Sony's FY ends March 31st.
We will get solid shipped numbers on October 31st when Sony reports their FY2017 Q2 results.
There you have it.
The PS5 Exists.