There are basically two scenarios.
1. Trump wins. In doing so, a giant window of opportunity has opened for the German SPD Party in making Trump the sole issue of the campaign, rather than facing the dozen-odd issues which most German voters are focused upon. Utilizing the German state-run news media, this campaign would focus on US-Russian relations, US trade agreements within the EU, the likely downsizing of US forces in Europe (particularly Germany), non-intellectual behavior by President Trump (something that intellectual journalists and politicians can't stand), and a likely stronger relationship between the US and the UK (which won't go well with the anti-BREXIT-crowd).
2. Clinton wins. The SPD Party is basically screwed. Their top vote mechanism is now lost and they have to focus upon the dozen-odd issues confronting the German public. While doing so, the likelihood of increased friction between the US and Russia will continue. The Merkel-led government in dealing with President Clinton? Probably a welcome visit in February with a major party or function in Berlin for her. President Clinton will let the news media know that she's all in for the SPD Party and their election chances in the fall of 2017.
To say there is zero effect.....is simply not true. In either case, there is a direct effect and change expected for the 2017 German election.
Trump as enemy number one? It's an amusing story-line which requires a lot of fictional writing and creative political analysts.
But you have to also add in this odd variant with a Trump Presidency. By late spring, the French Presidential election will have come and gone, and a right-wing President in place (99.9-percent chance of this occurring now). Add on several additional elections in Europe in 2017, and there's a fairly noticeable right-wing win statistic going up. So how do you sell the anti-Trump theme with so many right-wing wins going on within the EU? At some point, Germans would ask stupid questions and put the SPD-theme of anti-Trump into some tailspin.
You can basically put a 12-month calendar and settle back for a fairly rough German election with several curves and stumbles. As much as it sounds crazy, the Germans are hand-cuffed to the outcome of the US election.