I shall use 2014 flipped analogues as far as I can, not perfect.
Reid = Chambliss
Bennet = McConnell
Johnson = Walsh/Curtis
Kirk = Pryor
Portman = Udall
Ayotte = Begich
Rubio = T. Johnson
Toomey = Hagan/Warner (Lean Hagan)
Burr = Hagan/Warner (Lean Warner)
McCain = NY Gubernatorial 2014
Coats = Levin (Would've been Harkin if Stutzman were nominated, he'd have been the Braley...oh well.)
Grassley = Durbin
I'd say it's a bit more like this...
Reid = McConnell
Bennet = Chambliss
Johnson = Pryor/Landrieu
Kirk = Begich
Rubio = Harkin
Ayotte/Toomey = Hagan
Portman = Udall
Burr = Shaheen
McCain = Quinn/Malloy
Blunt = Hickenlooper
Coats = Levin
Grassley = Warner/Dayton
Anyway, I'd say:
Wisconsin
Illinois
Florida
New Hampshire
Ohio
Nevada
Pennsylvania
North Carolina
Arizona
Colorado
Missouri
(not really competitive)
Indiana
Iowa
I will go:
Reid=Harkin
Bennet=Chambliss
Johnson=Hagan
Portman=Shaheen
Kirk=Landrieu
Rubio=No good fit, Perdue/Harkin hybrid? Maybe with some Kagan/Warner/Udall elements?
Toomey=Warner
Ayotte=Shaheen
Grassley=Cornyn
McCain=Roberts
Coats=Johanns (that's not a prediction that Young will follow in Sasse's footsteps, though)
Blunt=Roberts
