I think at the beginning of Dragonborn, while we are riding the ship into the harbor, something will happen with Hermaeus Mora and we will be stripped of our perk points, essentially forcably resetting our perks. Hermaeus could be doing this for one of various reasons. Perhaps he favors this newly awakened Dragonborn and is trying to take you out of the picture, perhaps he has some grudge with you because of events in his sidequest (your time has come like Septimus's). Whatever the case, you will have your perks completely wiped out.
Throughout the DLC then, you will be seeking to regain your perk points to fill out trees that have been restructured and some possibly even dramatically redone. I anticipate smithing would see a nice overhaul (or I hope that at least) but new perks will be peppered throughout all the trees and they will have new linkages (possibly radically different linkages) between all the perks. You will regain power as you attempt to fight back against Hermaeus Mora, and eventually you will enter his realm to reclaim all of your old power. This culminates in a final showdown with the old Dragonborn and you have a no-holds-barred smackdown with him in Hermy's realm (because he is Hermaeus's new champion).
Alternatively, I could forsee you not having your perks reset initially in the DLC, but mayhaps you encounter the new dragonborn about halfway through, he kicks your a--, absorbs your soul (or the dragon part of it anyway) resetting your perks. You then go to Hermaeus Mora in your weakened state to seek a way to regain your power, or possibly the Divines will aid you in this endeavor. However it happens, you reclaim your perks from someone and get to spend them in the newly revamped skill trees.
So in a nutshell, the perk reset is a part of the main story and it is utilized to allow Bethesda to really tweak their trees to improve them and add new features into the trees. I think this would explain what they meant by saying "explore new paths" which some took to be new perk trees and others a respec option... well maybe it means something along these lines? Thoughts?