I actually have a few theories that Nintendo switch it actually going to increase PS4 sales..and I already think its hurting xbox 1 sales.

Nice I was wondering when I'd made this prediction, though I think I first predicted 2017 as peak the end of November 2016.

Sony is making all the right moves right now. They have the Destiny 2 Pro bundle on the market, and they've got both a CoD and GT LE console bundle on the way. If they get one for SWBF2 as well, those bundles are going to kill it in every country outside of Japan. No doubt in my mind PS4 will shatter last year's sales numbers.

Well, the console has been up year-over-year compared to all previous years every single month this year, so I wouldn't be at all surprised if it had its best year in general in 2017.

Looks like the OP's prediction is on pace to turn out fairly well.

2 January 2016 to July 30: 6.6 millions PS4 sold according to vgchartz
Starting of January 2017 to July 29: 8.4 million.

Damm and I remember people saying PS4 will be down yoy because of the switch and Xbox One X

I don't think it's increasing them, but I do think that they offer a different enough experience, and varied 1st party, that they aren't hurting each other. 

Xbox's problem is that there just isn't enough reason to own one. Not when its exclusives are on PC, now. And those exclusives are dropping in quantity and variety. While I do think some are waiting for the X, I highly doubt it's enough people to warrant the drop the XBO is having.