If this year is as bad for the GOP as 2008 was -- and I would say it is worse -- we are going to see most of the toss-ups go the Democrats' way. That is bad for Daines, Ernst, Collins, Marshall, and Graham -- and especially bad for Trump's fortunes in Iowa, Ohio, North Carolina, and Florida.
I've also compared this year to 1980, and in that year, the "Reagan Revolution" carried at least a dozen Republicans into the Senate. Now it looks like that several Democrats might be carried into the Senate in tandem with Biden's victory-and all of the Republicans you list would be the analogues to those Democrats who lost in 1980.