It quite depends on when 9th gen will launch. We must hope that Wii U and XBOne sales better and PS4 won't drop, because if 9th gen starts too early its performance leap will be shit. Anyhow, about OP prediction, with a 2018 gen start it sounds reasonable. I don't expect 8th gen to stay on the market 7-8 years before the next starts, but should it reach 6-7, a 2019 start, then the performance leap could be quite high, as the 7h to 8th was quite prudent, to avoid a bloodbath, so this time they'll be able to fully match the normal performance growth for a given price. BTW, should 10th gen start less than 10 years after 8th, then the chance it include VR devices as standard equipment could become very unlikely.
PS A 2018 launch should be enough in most cases to avoid sacrificing framerate, anyway, but should 9th gen launch earlier, then yes, also the framerate sacrifice to be able to show higher res graphics could sadly happen quite often. So let's cross fingers and wish all of the three competitors the best (obviously wishing the leadership to our fav ones, but without wishing the others situations tha force them to launch early).







