Nelson will go in Jan 2019 (assuming his health doesn’t fail him in the interim). He’s lucked out by having subpar opponents (20-year House incumbent Bill McCollum in ‘00, a massively unpopular Katherine Harris in ‘06 and the open-borders RINO Connie Mack, IV in ‘12). He’ll be almost 80 and will have a number of GOP contenders to run him out (although the weakest is the one who wants to run the most, Gov. Rick Scott), with AG Commissioner Adam Putnam will probably be the strongest contender.
I sense you are correct about Adam Putnam; he pretty much is a powerhouse here in Florida. I do think though his goal is more Govenor than Senate. That could all change of course depending upon depth of opposition and the scope of opportunity. As far as Louisiana, most Edwin Edwards voters have fallen to attrition and this Jon Edwards will find little value there. Voters in LA are sufficiently alarmed regarding the way forward due to Federal interference in tneir comfortable way of life and the parishes normally democratic reliable (north of the Red River) will glean little success. I sense the conservative groundswell generated by the morass coming out of DC should IMHO carry the day. One may note this was the tide facing Mary Landrieu in the General election and this coming election will exponentionally increase those numbers. Fear is a great motivator.