Soundwave on 26 May 2016
I actually think this XBox 2 has been in development longer than Neo.
It put Sony in a weird spot, where they obviously don't want this gen to end so early, whereas MS has no such qualms.
Sony slapped together Neo quickly by merely doubling the CUs on the PS4 GPU.
If anything it wouldn't surprise me if Neo is the product being rushed to market because Sony does not want to make a PS5 so soon but they caught wind of XB2. MS seems to view the upgraded XBox as more of a successor and a large scale change to their entire hardware business (upgradable consoles, Win10 cross platform, etc.), so it will be a large change to their hardware business, not just a "XBox 1.5" as Phil Spencer mentioned.
