God knows what it will be.
Here is the nightmare scenario (for this country, I mean):
1) Whatever this is raises the heat on the moderate GOP members, and Kavanaugh's nomination falls through;
2) There isn't time to nominate and hold hearings for a new person, especially since one-third of the Senate will need to be home campaigning;
3) The Democrats win the Senate;
4) The GOP calls a special session and tries to get a nominee through with a lame-duck majority.
That is the recipe for abject chaos, and a de-legitimized SCOTUS.
A nightmare.