AfD walked away in second, but jumped by nearly 9% over the last federal election. That’s a huge gain in momentum.

It depends on the coalition that gets formed, does the conservative party go with the center left party for 4 years of stagnation or break their word and work with the fat right.
They have done the later already on emigration, passing a non-binding resolution (with only one conservative vote against) and narrowly losing on the second round because their own members of parlament didn't show up to vote.