You may not be able to watch the spatial content on the iPhone itself, based on what the source is saying. However, it still sounds far more practical to take video or photos with a device you'll likely have in your pocket already, instead of dragging a chunky headset with its likely short-lasting battery pack out to your social engagements.
Since the iPhone 12 Pro, Pro iPhones have featured LiDAR sensors that enhance AR capture and content on those devices, as well as recent iPad Pro models. However, since spatial video and images go a step further, supposedly offering a fully 3D rendering of a scene to the Vision Pro's wearer, this may mean Apple has to add even more cameras to the iPhone 16 Ultra beyond the current main/ultrawide/telephoto/LiDAR combo.
We also wonder if Apple may end up creating a lower standard spatial format that iPhones can capture with their current camera set-up, even if it wouldn't make full use of the Vision Pro's potential.
iPhone Ultra is coming
We've not had an Ultra iPhone yet, and the rumor mill suggests it's a given that we'll have one next year. It's also possible we'll have an iPhone 15 Ultra this year, but it appears that it'll just be the iPhone 15 Pro Max by another name.
MacRumors' source warns that their information is "currently incomplete," but that's not surprising. There's still over a year to go until the iPhone 16 series presumably launches, so plenty could change between now and then as Apple starts trying to build its future iPhones.
However, it's likely just one week until the iPhone 15 series appears at "Wonderlust": the Apple September event scheduled for September 12. We've not heard about any Vision Pro or spatial computing-related rumors for the new iPhones, but one similar tip we've heard a lot about is that the iPhone 15 Pro Max/Ultra is tipped to get a periscope telephoto camera, which will unlock improved zoom capabilities compared to previous iPhones.