The PS5 will be available as a standalone box that will probably utilize some manner of disk or card as well as download again. (let's face it: to make downloading games that are in the gigabytes and beyond a "common" user experience is going to require serious UPGRADE to our communications infrastructure- something the cable and phone companies have been putting off for years. In my opinion, the internet should be something with a minimum 200 mb down and up that you pay $80 to connect to one time and you're good. Faster connection means a monthly fee, perhaps, but this kind of internet needs to be everywhere, not just places like South Korea.)
The XBox Two will be basically the same thing. Microsoft will still have the money to put another console out there and have it not win again. And again. And again and again, over and over, for the next 5 generations at least.
Nintendo will unite their home and portable console into something to be accessed in some strange form by SOME devices not Nintendo-made. Their device will be cheaper than the other guys, but have some kind of selling point other than Nintendo legacy IP and first-party titles to back it up. They will sell enough to profit a bit, and survive for another round. And another.
I will own all three, and play the best games for all three. Just like every generation.