Sony have to because if they dont. MS will dominate the 4k market with there affordable Slim model.
Im glad MS told there customers and future customers there plans. This doesnt lead to disapointment. I would hate to be that guy who buys a brand new machine only to realise that a bigger and better improved model came out a month later.
I also highly doubt that the Neo will be a $399 console, not if the Slim is roughly around the same price bracket using the same Hardware as before. Unless Sony plan on losing profits on system sales.
If the Neo arrives this year it will be competing against the vastly cheaper X1S which would be more appealing to budget gamers and 4k owners. The Scorpio will not have a rival if its a complete year away.
Ill wait and see.
