Given my current sizable balance, I have very slight worries. However, if AA wipes out AAdvantage, then what will be left will be a completely different airline. In essence, they'd have to basically start from scratch. Key corporate travelers and decision makers would revolt, and I would expect Citi and Barclays would be dragged into this given the amount of miles people 'bought' through them.
Net net, anything is possible, but closing/restarting AAdvantage seems like an unlikely scenario to me.