With the demise of the “old” Equation Editor 3.0:
MS has proposed 2 workarounds for nuking the old Equation Editor. The first is use MathType 6.9c. You can buy it for $50-97. There is also a 30 day free trial.
Comment from someone at MathType:
Bob Mathews | January 17, 2018 at 11:31 AM
The basis of Microsoft’s recommendation, “edit Equation Editor 3.0 equations without security issues with MathType” is that we (Wiris) worked with Microsoft to eliminate the security issues in MathType, and released a new version (MathType 6.9c).
Also, we recommend Equation Editor users download and install the MathType 30-day trial. After the trial period, it becomes MathType Lite, which is free forever, has essentially the same features as Equation Editor, and will receive the same security updates as a MathType registered version.
The other Suggestion from MS is to convert the old equations to LaTeX
https://support.office.com/en-us/article/Write-insert-or-change-an-equation-1D01CABC-CEB1-458D-BC70-7F9737722702
Insider students and educators: We heard you loud and clear! your top requested LaTeX Math Equation syntax is here.
Available for subscribers in Version 1707 ( Build 8326.2058) and higher
I have read about a 3rd possible fix. Buy a product from a company called “0Patch”. They provide microcode updates somewhat like the one MS released in November.
2018 01 16- MICROPATCHING BRINGS THE ABANDONED EQUATION EDITOR BACK TO LIFE
https://0patch.blogspot.ca/2018/01/bringing-abandoned-equation-editor-back.html
So Woody, do you have time to research, interview 0Patch to see if they are for real?
– Ron