Oh wow you certainly did not convince me even though you tried hard by listing Knack 2 and a few others that will move an insignificant amount of hardware.
Good deals, low price etc.. I hear that every year. 2017 isn't special in that regard.
The Division, Battlefield 1, FFXV, Overwatch etc. sold well too. Nothing is set in stone yet. Delays will be obvious.
So like I said. 2017 looks pretty much like 2016 just without PSVR, Slim and Pro launch.
You're welcome to name the "few" others out of the ones I listed that would be insignificant considering I only listed a "few" you're saying the majority of what I listed is "insignificant", it would also be nice if you didn't reply with such an attitude. Not sure why you think it's "trying hard" it's not like I missed anything from 2016 other then the annual MLB game (which I also missed off the 2017 list.) I could "try hard" if you'd like though and add Wipeout Omega Collection, Everybody's Golf, and also put Detroit, Dreams, Spiderman & God of War as potential 2017 releases.
And as to everyone repeating "PSVR, Pro, Slim." as if that'd offer 2016 such an amazing boost. If anything these products will offer more in 2017 then they did when they launched. PSVR suffered from awful stock shortage, Pro suffered some shortages, and 'Slim' is just a replacement for the OG PS4 and offers nothing over the original, it's not something that's going to BOOST sales other then a lower price.
Holidays 2017 will be the first major deals on both Pro and PSVR, though PSVR isn't going to have a large impact, I think a cheaper Pro without shortages will.
There's no denying that the exclusive line-up for 2017 is leagues ahead of 2016, combined with a $200 slim deal for the holidays and a $300-ish deal on a Pro, and what I believe will be a stronger showing for Third Party titles (especially considering PS4 always has a CoD Bundle, & will likely have a RDR Bundle too) I expect the PS4 to have it's best year.
If I had to give a range 16.5-18 Million, so a slight decrease is in the range I think is plausible at this time, but I think it has a greater chance of increasing YoY and that's what I expect.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)