A bit late to the party, but I just wanted to throw my two cents in.
He directly answers the interviewer's question if there will be Scorpio games that can't be played on XB1 by saying that is not their plan. Their plan is that all games will be playable on both the original XB1 and the scorpio.
I'm of the opinion that both Scorpio and Pro will eventually get games that are not playable with the original model. This will happen when their respective successors are launched.
See, my thinking: we are entering the age of rolling generations. In the future there will always to overlapping generations that share a library.
But, when PS5 (or whatever it's called) is launched, there will be a generational break. From there on, all games are playable with Pro and PS5. PS5 will also be fully compatible with all PS4 games, but PS4 will not be able to run games designed for Pro/PS5 generation.
This will have several advantages.
First, there will not be a start of the generation drought. There's already a huge library to play with, and more are released all the time. Consumers are happy.
Second, publishers will not need to worry about the small install base, because there will be an existing base of tens of millions already. Publishers are happy.
Third, platform holders raise exit barriers: when you are already invested in the ecosystem, you are more likely to purchase your next console from the same family. Sony is happy.
This way we could be getting new generations every three years, but the actual break would only take place every six years. (Unless you are one of those weirdos who always need to upgrade to the newest model. o/ )
If I were working for SIE, this would be my plan. I don't know about Microsoft, though. With Scorpio being a bigger technical leap than that between PS4 and Pro, they might cut XBONE earlier, so they'll be in a limbo of not-quite-big-enough install base to make this model viable.