Current polling has the Union around 30%, AfD around 20%, SPD and the Greens around 15% and several smaller parties (FDP, BSW and the Left) near the 5% hurdle. All relevant parties excluded a coalition with the AfD. Most seem to expect Union+SPD. But depending on how many of the smaller parties make it into the Bundestag, Union+SPD might not gain a majority of seats and a coalition of three parties might be the only way to achieve a majority without the AfD.
Resolves Yes if, excluding the AfD, a coalition of at least three parties is necessary to reach a majority of seats in the next Bundestag.
Resolves No if two or less parties, excluding the AfD, can reach a majority of seats.
There doesn't need to be an actual coalition or government, what matters is the distribution of seats after the election. At least 316 seats are required for a majority.
The Union (CDU/CSU) count as one party.