I think you've embraced the popular misconception that the question the Supremes must rule on has to do specifically with Trump and that is not correct. It has to do with Presidential immunity, dealing with the office itself, regardless of who inhabits it.
I believe one of the considerations they must deal with is the possibility that since the Democrats have normalized doing everything in their power to prevent Trump from being elected again, what happens when the Republicans, or any other group, uses the same law fare techniques against past or future presidents. Without some form of immunity for those holding the office, I can't imagine anyone voluntarily holding the post.