I think it's important to clarify that the balancing for exotics already happened in this week's update. So, to take the Bad Juju, for example, it now fires 8 bursts instead of 5, and so on for all the other weapons mentioned in the patch notes. That's already happened and works fine in-game, right now.
What's being discussed here is that the DLC that hits next week will include new exotic weapons and armor with higher damage/armor ratings and light levels. You will also have the opportunity to upgrade any current exotic gear to the base damage/armor/light levels of the new DLC exotics. Doing so will require an exotic shard and 7000 glimmer for each piece, and then you'll need to re-level the gear.
Now, this is way too expensive- both in terms of materials and time, but it's just a new upgrade path. It's not like the exotic gear you have now becomes obsolete if you don't upgrade it.