The 4 Romney seats are toast in a Dem midterm
I think OH and WI would flip before MT and ND. But yeah, it'll almost certainly be Republicans if Clinton wins the presidency.
OhioKasich vs. Brown is Safe R.
Tiberi will make it Tilt R in a neutral year, Lean R in a small wave, Likely R in a 2010/2014 sized one
Mandel would do better than in 2012, tossup in a neutral year, Lean R in a big wave
WisconsinI think Duffy will run, if so, he'll overperform Walker, he is less polarizing than either Walker or Baldwin, will be favored unless it's a Dem wave. Tossup in a neutral year, Lean R if R wave.