What would happen is that it would further divide the fandom (If that's even possible at this point). The fans who supported the ending would most likely leave and there is no guarantee that the ones who left the series would come back.
Besides, merely changing the end pairings won't solve all the other problems that the ending brought about. It would just be the same kitten with different pairings.
Keep in mind that I'm not against changing the ending, if it's done correctly. However I don't think Kishi would be able to pull it off without making things much worse.
Edited by TerrorKing, 05 November 2015 - 01:39 PM.