I don't think this is true at all. MS could easily establish themselves a base of non native Xbox users if they launch a new system in late 2017 that is significantly more powerful then PS4. Hardcore console gamers may very well move to the system if huge third party games like  GT6 and Elderscrolls 6 are running on it outputting superior graphics+performance then the PS4 and PS5 is nowhere in sight. The established Xbox fans will be there of course and their loyalship isn't down to being the most powerful otherwise X1 wouldn't have sold 10m in its first 13months.

By 2017, 14nm chips will be available alongside "next gen" AMD CPU/GPU technology and HBM RAM.

Not to compare Xbox brandpower to Playstation but PS1/PS2 shows that once you're on a role, having slightly less pretty games then a new competitor isn't going to bring your momentum to a hault.

If microsoft can deliver software which can deliver graphics that "look" similar to Epics recent UE4 kite Demo then it doesn't matter too much how much more impressive the PS5 graphics are as Xbox10 will still be a huge leap and diminishing will make PS5 look only marginally better.

Unless they have a gimmick up their sleeves, arriving early is the only way to securely gain audience, otherwise they just have to hope that sony messes up like they did with the PS3 launch.