Mr. Gold has every reason to eliminate dark magic since he/Rumple is constantly paying the price for using it, just like that Dark One predecessor. Dark magic leads to unhappy endings. But the restoration of happy endings leaves room for lots of light magic to support everyone’s dreams coming true.
When Sheriff Graham started remembering after kissing Emma, he began wandering desperately in the woods. When David started remembering after a hypno-regression session with Archie, he panicked. When Jefferson connected the dots, he held hostages at gunpoint. All this supports what Dorothy said:
I don’t mean to be a kill-joy, but I’m just saying this could get ugly.
On the other hand, both Henry and August appear to have total recall of FTL and individuals’ pre-curse abilities, relationships and happy endings. Neither is going crazy in SB. Their knowledge appears to be a comfort to them. So I’m hopeful that they will discover ways to serve as catalysts for the curse to self-destruct and for the evil characters to become their own worst enemies.