I just thought of something that could solve the third party problem.
Before working with Nintendo on the NS NVIDIA had their own line of gaming devices that could stream PC games called SHEILD. They were working on a second one before it was cancelled due to "business reasons"
NVIDIA SHIELD 2 Tablet has been canceled
What if this deal with Nintendo goes further than simply supplying hardware for the system? What if, maybe through a different dock than the one that comes with the system, you could stream PC games when you're playing at home? That would be one hell of a game changer and would ensure tons of games available on the system from third parties even from day 1.
Of course this is just a thought and unlikely to happen but man would it be cool. It would sure be the kind of thing to put them on an equal playing field as PS4 and XB1.
Edit: after further research I found that it wouldn't work in the way I thought it would. You would need your own PC to stream games from. Oh well.