Korra stated that she thinks her link to the past Avatars is gone forever, but that is what Korra thinks and doesn't know. The creators could make it so that Korra does regain her link to the past Avatars because Korra stated that she thinks her link to the past Avatars is gone but again, she doesn't know.
Korra did not lose her connection to her past lives, her connection to her past lives may be weak but it is not gone. I refuse to accept that her link to the past Avatars are gone and I have a good reason to refuse believing that Korra lost her connection to her past lives.
Korra is the reincarnation of Wan. As we all know, Wan is his own being. Wan can exist without Raava. As we all know, Korra was able to exist without Raava.
If Korra isn't the reincarnation of Wan then she wouldn't of been weakened when Raava was attacked and the past lives were wiped from existence because Raava and Korra/Wan are two seperate entities and they can exist without each other. If Wan and Raava were truly bonded then Korra would not of lost her link to Wan and all his incarnations, because Korra is Wan's incarnation.
If Raava was responsible for Korra's link to her past lives then Korra really isn't the reincarnation of Wan because as we all know, Wan and Korra was able to exist/live without Raava, and if Korra is truly the reincarnation of Wan then she wouldn't of lost her connection to Wan even if Raava was destroyed because Korra is the reincarnation of Wan and will always have a link to him.
Whether Raava was responsible for the current Avatar's link to his/her past lives or wasn't responsible for the current Avatar's link to his/her past lives, the current Avatar will always have a connection to their past lives, so the creators made a hurp durp situation.