I'm looking at the total system sales and how fast the system is selling. The PS4 has already surpassed the Wii U, but the Xbone appears to be struggling with surpassing the Wii U, even though it has more 3rd party support.

I'm really not too sure, and neither is Sony. Sony even said themselves they didn't know why the PS4 was selling so well. My guess would be that initial momentum Sony had a year ago. Some are predicting that momentum will end soon. As for me, I honestly just don't know.

I think you're basing this from what you've been seeing this generation. That's fine and all, but the video game industry spans back over 30 years, and according to 30+ years of historical data, exclusives sell systems. This is also the case with other mediums such as VHS vs Betamax and etc. The content was on VHS, so it sold better.

As for console gaming, there's a significant shift in console gaming sales. The console market is shrinking, while the PC gaming market is growing (and very rapidly). I don't believe that the PS4 sold because it was the console people wanted. I think people felt that perhaps there was no other console solution to go to other than the PS4. As the months went by, gamers started to realize that their games weren't running in the fidelity they were promised and began migrating over to the PC. 

Well, also look at the quality of those games that are selling. You'll notice that a lot of those big games are rated poorly, because they're over hyped and over marketed. I think what's really happening is that consumers are losing confidence. I say this because the console market is shrinking while the PC gaming market is growing. Eventually, games on these consoles may not sell as high anymore due to how so many people are being misled. When a product loses consumer confidence, it usually dies.