Perhaps this is a Sierra-related problem?
Thank you for posting the issue you're seeing. The inability to open scene files that have been modified in Xcode 8 is a known issue that we are currently looking into. However, I would greatly appreciate if you filed a bug report for the issue you're seeing in which reverted files are still not opening in Xcode 7.3.1. The more information you provide, the faster we'll be able to reproduce and fix the issue, so please attach the reverted scene file that you're unable to open, and provide us your configuration details.
Once your bug report is filed, please let me know the bug ID so that I can quickily access it and continue communication with you.
Logged as 27734495
I was using Xcode 8.0 spritekit editor as a workaround. Because it didn't crash and now includes a scene heirarchy.
But with beta4 that seems to crash too.