McConnell is now far down in the polls. Less than 45% favorable last I heard and that was in the week following Ted Cruz exposing him for his lies about no deal to fund the corrupt Ex-Im Bank.
Further, he won as an incumbent by only 59% in the match against Bevin and Bevin was not such a great candidate.
Ergo, McConnell is very vulnerable now.
McConnell is not up again for re-election until 2020.
Kentucky will handily re-elect Rand Paul to the US Senate in 2016, and if we still have a country, they will re-elect Mitch in 2020 (if he manages not to be hung for treason).