Holiday 2019 is perfect. That gives PS4 a long and healthy 6 years on the market. By then, KH3, shenmue 3, god of war, ff7 Remake episode 1 should all be out for PS4.
Ps3 as crazy expensive for Sony as it was, had 7 years on the market before PS4 launched. PS4 was conceived much cheaper and has had a much more profitable lifecycle compared to ps3 which means PS4 is probably much closer to being replaced and moving onto next gen.
PS3 was only on the market so long cause it cost Sony millions of dollars and needed the extra time to recoup. PS4 has actually made Sony lots of money and doesn’t need to wait as long as they did last gen to introduce a successor. 5-6 years has always been the norm anyway. Last gen was just an outlier.







