Subscriptions, subscriptions, subscriptions.
Nintendo - outsell PS4 using 1st party and 'low end' 3rd parties. The $20 subscription is gonna quickly become a $60 subscription. They'll try and use their back catalogue to get to $60 but they may be forced to use more recent software.
Sony - aim for PC gamers. PS5 will be an extremely capable home console. Sony games will appear on PC. Sony will differentiate from the PC experience and use tech to provide a better console experience. Download ANY game pre-release so that it's ready to go. Every game supports cross platform play. Insta-load using SSD, suspend multiple games at the same time, simplicity. etc.
This will be the first time Sony does more to provide a console experience than Nintendo since PS1. They'll teach Nintendo a trick or two. The PS5 will do more than ever this gen to show why the console experience is better than PC.
MS - Swallow everything. They've already started. MS will use XB to push Windows. MS is gonna pretend they don't care about consoles. This is a lie. They know that the only way they have any future against Google and iOS is with the 'cazual' game consumer. XSX will be capable of Windows and will be capable of running the PS games that come to PC.
Hate to see/say it but this site could become irrelevant. Subs are gonna determine the winner not hardware sales. It's gonna be the Netflix/Amazon war while VGC is focussed on measuring box office. Adapt or die. (Please adapt).
Nintendo is gonna win the (traditional) console war ie Switch will sell more than PS4 and 5. Sony will sell less consoles than Nintendo but beat MS. MS will make more cash via subs and will be closer to the winning Netflixish war than Sony or Nintendo.
Everyone will win this gen depending on how you measure it.