Well... Pretty much according to the whole story line of MKDA, Scorpion's ending did happen, that is, he did pull Quan Chi with him into the netherealm... So, that was the last we've heard of Quan Chi in MK4... Honestly, I don't think that Quan Chi's ending happened... For a few reasons:
In Quan Chi's ending, Shinnok tells Quan Chi of the gift of his existence... I think Shinnok knew that Quan wasn't gonna be happy about that... So I don't think that he would have told Quan that, not until their mission was complete.
Secondly, I think that one of the good warriors had killed Shinnok... Otherwise, what? It's like... There's this big war against Shinnok, and all of a sudden every good guy's like "What? Shinnok is dead? But who killed him and what happened to the amulet." U know? Besides, Liu Kang's ending states that he DID defeat Shinnok, and according to Kitana's ending in MKDA, it was confirmed that Liu Kang's ending in MK4 did happen. Therefore, my conclusion is that Liu Kang, "The greatest hero of them all" Had killed Shinnok.

(I'm not like those other ppl who are obsessed w/ Liu Kang cause he used to be the main hero, I actually resented him for that"

part of quan chis ending did happen though..he got the amulet....doesn't mean the bad guys won..he just got it.

i dont feel like going through all endings..just watch them and then look at the mkda storyline

like play kang's ending..u see the whole kitana scene..well that is mentioned in mkda..so part of his ending happened

Raiden's ending happened as well; in MK:DA, he relinquishes his status as Elder God, which was rewarded to him after the war against Shinnok. I think only his, Scorpion's, Sonya's and Liu Kang's are the only ones confirmed to have happened. Johnny Cage's and Fujin's endings could have happened too, but they don't seem to be that important to the storyline anyway.

I think these endings happened:

-Raiden (he confirms it in his ending in mkda)
-Scorpion (quan chi was in the netherlrealm before MKDA)
-Fujin: It is confirmed in MKDA

In mk gold

-Kung lao (Goro was an ally before MKDA)
-Kitana (I think that she killed mileena)

I think those are the endings that did happen.

Liu Kang simply said that he helped defend the realm of Earth. Not defeating Shinnok. And it was Rayden who stated that he personally beat his ancient enemy.