The whole situation just seems loosely slapped together and I cannot see a reasonable way for it to be executed. I get that this is early and whatever but, um, seriously? Sin is back, despite Yu Yevon being killed, which means that there needs to be a way for a) Yu Yevon to come back or b) Sin to be created anew. If B then why? And why did it take so long?
Tidus and Yuna calling off their relationship after so much intense desire to find each other at long last ugh it's just, the relationship was crazy but it worked and having them go "oh actually nah" is just preposterous. I can get, maybe, that they grew apart during peace because smurf that is a real phenomena but it's not a concept I think Square Enix could pull off in a thousand years.