I agree with this:
Also from the point of view of the Greens, the proposals of the SPD general secretary are not the answer to everything." A boring movie will not get better if you air it longer", said the domestic policy spokesman Volker Beck. "Policy must become more distinguishable again. And as to that we all have to look who's talking."
Not only in Germany (but also here) many reliable old voters are dying, while being replaced with unreliable younger voters. That means turnout is going down further and further.
No additional measures can halt this process really.
The Austrian states of Styria and Carinthia introduced an early-voting day in the mid-2000s, because turnout fell in state elections.
Instead of boosting turnout, it still went down. While not nearly as low as in the US, it still decreased from about 80-85% to ca. 75%.
The only scenario in which turnout increases these days is if there's an exciting and close election campaign going on that draws people to the polls, mixed with a good political climate (no political scandals).