This whole shit show does not surprise me one bit. As soon as I saw the news, I knew Mitch would push for a vote and the Ds would use the 2016 example as a reason to not vote. In the end, it is about power, and the Rs cannot pass up the chance to add a third Justice to the court in a four year period. This is a conservatives dream, so of course they are going to put forward a name and press for a vote.
Now, this may shock some on here, but I actually agree the Senate should go through the process of naming a replacement. The President's term does end on 1/20/21 and he has the right to name a replacement. The Senate should do their due process to vet that person and start the process. If it bleeds into past election day, then so be it.
It gets dicey after that, as in a lame duck, some Senators may be voted out of office and states like GA and AZ may seat some of their Senators during that period. That may lead to the Senate either delaying or voting down the nominee until there is a new Congress in early Jan.
I do expect the Senate would rush through a nominee though, probably during the lame duck. People will be very upset, but it is what it is in today's political world.
I also think this may rally the Ds to radially change the Senate if they take the Senate, which they are slightly favored to do right now. If that happens, goodbye filibuster, hello maybe an expanded court, and statehood for DC and PR.
On a final note, if the court does go 6-3, it may force Congress to grow a pair and actually start to take back power it has conceded to the other branches. I'm not sure that is a bad thing in the long run. As a conservative court and an activists Congress that reasserts power may be a sense of balance.