I heard this mention in a TWAB a while ago, mentioning something happening to the weekly bounties. I read about how there is going to be some sort of new account-wide tasks added in BL that give out more XP than weeklies...BUT I'm not sure whether they meant they are completely removing all weekly (like being replaced) OR those account-wide tasks are just an alternative, and weeklies are staying.
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To my understanding they are removing the bright dust you can get from weekly bounties so there will be still be weekly bounties but they do not award BD. You will now get BD from the account wide quest.