Hi David Jaffe1
Welcome to Microsoft Community.
Based on your description, I understand that you want the development team to come up with a mixed reality alternative as soon as possible, and I understand very well how you feel!
Please allow me to explain for you that I am just a support person, not a member of the Windows development team.
First of all, thank you very much for your long-term support and use of Windows. I very much understand your current distress and dissatisfaction, and I apologize for any inconvenience caused by the removal of the Windows Mixed Reality feature.
Regarding your suggestion of rolling back to a previous version, as you mentioned, this is a viable interim solution. It's also my own temporary solution when using it in my daily life, but I know it's not the final solution.
Unfortunately I'm not part of the team involved, I've sent your request and comments to the team involved via the feedback center, and I hope they will understand and take it seriously as soon as possible.
You can submit your ideas and suggestions through the Feedback Hub(Send feedback to Microsoft with the Feedback Hub app - Microsoft Support), and the development team will regularly review submissions for ideas or fixes.
Please share the feedback link here after submitting as it will allow others on the forum to vote for your submission, including me. More votes will lead to more visibility and higher priority to the development team.
Thank you for your understanding and support, I really appreciate it!
Hopefully this issue will be handled properly soon!
Best Regards
Arthur Sheng | Microsoft Community Support Specialist