Although the PlayStation 4 Pro will allow 4K video streaming through apps like Netflix and YouTube, we learned after the Meeting that it won’t support Ultra 4K Blu-ray discs. According to Sony Interactive Entertainment President Andrew House, who spoke with The Guardian yesterday, it isn’t possible to add support for UHD discs in a post-launch firmware update. He then said they’re more focused on streaming with 4K, as it’s what consumers are leaning towards:

Our feeling is that while physical media continues to be a big part of the games business, we see a trend on video towards streaming. Certainly with our user base, it?s the second biggest use case for people?s time on the system so we place more emphasis on that area.
In their PS4 Pro FAQ, Sony said, “No, PS4 Pro?s internal Blu-ray drive does not support the new Ultra 4K Blu-ray Disc format. It supports the same Blu-ray Disc specs as the standard PS4. The Blu-ray Disc Player application, however, will support high-quality upscaling of DVD and Blu-ray Disc content.”
Sony added that there aren’t any plans to sell 4K movies or TV shows through the PlayStation Store at PS4 Pro’s launch, “but the PlayStation Network team is looking into it.”
Sony announced earlier this year that they’re expecting to sell 20 million PlayStation 4s by March 31, 2017. As House confirmed, “Pro sales are factored into the 20m units that we?ve said we?re going to sell this ...