Why would the supreme court agree? Where does the constitution or federal law give the executive branch immunity from prosecution?
I think the argument would be that the Constitution provides for impeachment pursuant to a particular procedure. If you want to upset the decision of the people, then you need to follow that procedure. You can also see that adventurous prosecutors might use their power to conduct politically motivated criminal prosecutions of the President if that were not the rule. It’s not a slam dunk, but the Obamunists are probably putting their chips on that result in order to protect Hillary.
And if she loses, then they will not care so much if she’s indicted. They will hope that the rest of us won’t care so much if she’s not indicted.