No - the Republican seats in those states are expected to be targeted by Democrats in 2018 (Sen.Heller in Nevada and Sen. Flake in Arizona).  There is speculation about Sen. Hatch retiring, but that won't change things much, for he is in a state that typically leans Republican.  

All in all, the Democrats will attempt to defend 25 seats in 2018 - the Republicans only 8.  Of the 8 seats the Republicans hold, 5 are considered solidly held....The likelihood that Democrats will win the Senate in 2018 as Michael Binder inferred is virtually impossible.