They won’t, in no small part because the AfD has enough seats to block the attempt.
They cannot block a decision of the federal constitutional court, don’t be ridiculous. Germany has measures in place exactly for this scenario, and they are about to be enforced. They cannot be vetoed away, it’s a legal matter.
Read the article. It’s already happening.
You don’t seem to know a lot about the German constitution. The opposite is true. Unppular fringe groups are not banned because they are not actually a danger to democracy, as long as government positions are not in reach for them. That’s exactly how the german federal constitutional court has argued in the past. Successful bans ever only targeted actually successful parties.
The core mechanism of democracy is to protect itself, and first and foremost that means protecting itself from facism. A political organisation that’s threatening democracy should obviously not be allowed, so it will be banned.