Er no. Dont agree. NX is 2017 imo, and Xbox One and ps4 will be around for along time yet.

PS4 and XBone will be around for a while. Unless VR takes off like a rocket (which I doubt) and they need more power inmediately, I can see the XBone waiting until 2018 and the PS4 until 2020. They will be cheap, profitable and with enough horse power to keep multiplats happy for a while.

Nintendo is the only one that needs their next gen hardware out in the market as soon as possible. A 2016-2017 release is inevitable.

if that's all PS5 will do than it's in trouble

Holiday 2019 or early 2020

2020. There's no need for stronger hardware before. Sure, you could up the resolution or the frame rate a little, but it wouldn't be enough to justify another 400 $ from your main audience. If PS5 released in 2018, games would just continue to come for PS4 with just minor graphical differences. Only enthusiasts would throw out another 400 or 500 $ for new hardware, the masses would just stick to their old console. The sales of the successor would be horrible. That's why new hardware needs a serious step forward and right now, there's nothing like that on the horizon.

Also, Sony and Microsoft will want to wait until SSD are cheaper. HDDs are not an option for next-gen, they would seriously hold back the speed of the devices. So once you can get a 1 TB SSD for about 50 bucks, that's when you will see Next-Gen.

No earlier than 2019. Maybe 2020.
I know some wishful thinkers hate that thought. Too bad. This isn't the "midpoint", it's just getting started. Midpoint will be 2017.

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.

Next nintendo handheld in 2016, home console in either 2016 or 2017. xbox something in 2017 or 2018. ps5 probably in 2018.

I think whenever they do launch, MS will likely try and get the jump on Sony by a year. If they're smart they'll be starting to prepare exclusives for the next gen launch around now and launch it around 2019. They may well try and repeat history with the XBone as they did with the original Xbox however and ditch it much earlier. It could be as early as winter 2018, especially if by some miracle the NX gains traction. I also know by posting this I'm likely to get someone screaming at me telling me how wrong I am instead of discussing it, as happened with the loon in the rise of the tomb raider sales thread.

Next Xbox: 2018-2019
Next Playstation: 2019-2020