The Supreme Court is going to be 5-4 for a while. Roberts is more conservative than Kennedy and he's going to be seen as the "Swing" pick. But for sake of argument, its going to be a solid 5-4 majority for quite some time.
The Democrats have to win the Senate or pray for good health. Ginsburg is 85. Breyer is 80.
If they won the Senate, they could block Trump from appointing anymore extremist right wingers.
Trump and McConnell are packing the federal courts right now. The media really doesn't report it but they are appointing so many judges.