I agree with your premise idea that future consoles will be more about locking you into a know market place and having your old games run on your new hardware, but I don't agree on your dates.
For Nintendo it all points for a 2016 or 2017 release, there are two machines and we don't know which one will launch first and how will they work. But for MSoft and Sony you're being too optimistic.
Both the PS4/x1 were launched in late 2013, and we should expect at least 5 years for them if only to allow the next consoles to offer noticeable better performance than the current offerings. Personally I expect the PS5/XNext to be launched close together in either 2019 or 2020.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.
