So with Nintendo releasing the NX next year, that officially starts the 9th console generation which Sony and Microsoft usually joins in after a few years which the 8th generation started in 2012 with Nintendo and 2013 by everyone else. However at this E3 2016, both Sony and MS will be announcing newer and more powerful systems which is obviously being done to fully support the power hungry Virtual Reality gear that is coming out.
Though their names may be similar to the 8th generation names, their higher power easily makes them a newer console to fit in a new generation.
Time will tell if they are a decent enough leap in power and capabilities to be a whole new generation. Seems like VR is the reason its happening though, old consoles not powerful enough to do a decent job it would seem.
I think VR could be one of the reasons that new consoles will be release sooner. The console makers like Microsoft, Sony, and Nintendo probably want to release newer consoles because they want to earn more money from a sudden rush of new buyers who buy new consoles.
Plus, console makers may want to release consoles sooner to get more sales in the near future.
Console makers maybe afraid that there would be not as many console buyers in the future from less active gamers, kids, teens, young adults. and casual gamers which will be happy only playing games on their PC, settop TV box like Apple TV, Fire TV, Nvidia TV, and Android TV, smartphone, and tablets. There are gamers who are fine with not owning a console because their PC and mobile device have enough games to satisfy their gaming needs.