One reason I don't think it's at all paranoid to suspect that the Republicans have deliberately taken over the voting system in order to cheat is that they keep doing things that don't otherwise make sense. There's a rather long list of things you just wouldn't expect them to think they could get away with unless they really thought they could control the ballot box, because otherwise they would have to expect that the public would kick enough of them out to not only end some political careers but also make impeachment - and prison - a distinct possibility.
And then there's this nuclear option thing - why would they be willing to remove any possibility of stopping majority party initiatives unless they were absolutely sure that they could never become the minority party again?
Conservatives have made good use of the filibuster over the years, on judicial nominations and a lot of other things. Are they absolutely certain no one will wake up and get rid of them? Or are they just sure that how we vote isn't going to matter?