They will be a threat as long as they exist because they've made it clear what they're willing to do, but they're much weaker than they used to be and they will likely remain in that state the way things are now. They are hunted like never before, chased into whatever holes they hide in and blasted out of them. This will be the case now and forever, they have never been chased so relentlessly and will never be given time to truly regroup.
I believe that al-Qaida is dangerous, but not more dangerous than ever before because throughout Obama's administration, we have made great headway in reducing and minimizing the danger that al-Qaida presents. Because of that, I believe we need to focus more on in-country problems now. I believe that danger exists, but danger always exists. But more than ever? No.
The fact that Osama bin Laden is dead was definitely a huge blow to al-Qaida. That, however, does not many that they are still not a major threat. As of now, I'd say they are less dangerous than they were around 9/11, but that could change. The way things are going in northern Africa, along with Obama's weak policies towards it, might be a recipe for a dangerous al-Qaida.
The organization known as al-Qaida is not more dangerous than ever before. It is most likely suffering massive losses of money, power, people, and resources. They cannot move around as freely as before and due to the number of wars being fought on multiple fronts, they are probably spread so thin as to be ineffective.