Even if you somehow project every single point of discussion into one dimension, isn't this a weird axis? It seems like there are a lot of issues in the US which no sane party argues about in Germany (e.g., separation of state and religion). If you were to do a factor analysis after presenting the same polls to parties in Germany and the US you will probably end up with an axis which neatly separates everything by country...
> I think we'll also see the AfD reach a two digit number -- I hope for less than that, but less than 5% (which is the minimum for getting any seats) seems unlikely.
I hope that you're wrong and at least according to current polls >10% doesn't seem like a forgone conclusion (https://de.wikipedia.org/wiki/Bundestagswahl_2017/Umfragen_u...).