Anytime you can get 6 out of 10 people to agree on something you have a groundswell of epic proportions. But the way Germany is governed means that everything is a compromise. The biggest party, the CDU, carries only 30% of the public vote. It takes 50% to form a government. That means that even if the AFD gets into the 30% range, it will form a compromise government with another party that is pro-immigrant. Some of those 6/10 voters are in other parties and it is unlikely they will vote for AFD candidates. It would be like a Democrat forsaking Bernie or Hillary to vote for Trump. Some may but most won’t.
The CSU is feeling pressure on the immigration issue. Even if the CDU sticks with the SPD and holds the Merkel line, the CSU might be turned to the right.