Might depend on how well NX does and whether it affects PS4 sales. If they can do a 4.1 and bring performance up to NX level it might be worth doing. If not then might as well just keep working towards a PS5 for 2018/19 release.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix