As much as you may want the NX out sooner, it will be a failure if it comes out too soon. Dance around it all you want, it won't change reality. Mid gen releases are the horrible strategies and never work. Facts will always outway what anyone wishes to happen.
I'm a bit confused.
Mega Drive launched way before the SNES.
Dreamcast launched a year before the PS2, but then PS2 launched a year before both Xbox and GameCube, so that gen was staggered over 3 years. What made the PS2 the right time for that gen?
Xbox 360 launched a year before the Wii and PS3.
I dont think "mid gen" has ever really been a thing. Releases have always been separate. How long is a gen? The PS1 and Saturn were hitting shelves this year at this stage in the SNES's life (compared with when Wii U hit the market). The 3DO and such were already on the market.