PS4 Slim and XBOne Slim will obviously be the most successful new versions of existing consoles.
Beefed-up versions Neo and Scorpio will be more niche, the higher the price, the lower the sales.
PSVR will probably be amongst the most successful VR devices of this generation, but this means very little, I wouldn't expect either an utter fail or a cosmic success, rather something inbetween.
NX will probably succeed, Ninty won't repeat the mistakes made with Wii U.