First off, this kind of goolish speculation isn't right.
Second, even if it were, both of the people you mentioned would be replaced by Dems anyway. WV's Gov. is a Democrat, and Mass. has a law (that was passed when JF'nK was running) that calls for a special election, and doesn't allow the Governor to replace him. And even if it didn't have that law, it'll have a Democratic Governor in less then a month.
Last month, there was speculation that he was one of the Democrat Senators being discussed by Abramoff. Reid is from Nevada, which has a Republican governor.
If Reid goes down, that's another Republican added.
-PJ
And as a party, they have a lot of old people in the Senate, more so than the GOP. So a death watch on members in the Senate would primarily focus on the Rats.