A week or so ago the scenario writer explained that FFX-3 is a possibility and now we get even more hints. The Japanese Version of he HD remake includes a drama CD which hints strongly at a FFX-3.
Someone at Neogaf actually translated the main story
Chuami harbors resentment towards Yuna, most likely because of the Auron father thing and also because Chuami actually dislikes Yevon, and Yuna has been doing nothing but praying at the Besaid Temple to a fayth that no longer even exists. Chuami thinks it's bullshit.
A second shoopuf has appeared at Moonflow. In FF10/10-2, the shoopuf at Moonflow is supposed to be the last of its species, so the mystery appearance of a shoopuf who happens to be quite close to the last shoopuf (a sphere of them is described in the audio) is a bit alarming. Thirty years ago the last shoopufs were a couple, but one of them died. My understanding is that Chuami and Kurugum ask Yuna (at Baralai's request) to investigate, and then go Bevelle to meet with Baralai about it. When Yuna refuses, Chuami uses Tidus against her, saying that Tidus is in Bevelle and he seems to be injured, which immediately sparks Yuna's worry.
Yuna agrees to go after consulting Wakka and Lulu, who also come along.
The fayth are acting weird. What fayth normally show are memories or just images of dead people. However, at the Moonflow the traveling crew witness a fayth image respond to a child's question like a sentient being. The child begs her mother to come back, and the mother answers in affirmative.
This later relates to the reappearance of Sin at Bevelle, implying that someone wished for Sin to come back.
In any case, when Sin reappeared, they realize the problem of trying to defeat Sin when summons no longer exist. Wakka and Kurugum defer to Yuna, waiting for her decision on how to handle the new Sin, but like an airhead she says amidst all of this that she must meet Tidus.
So Chuami's pissed and she decides to eavesdrop on Yuna and Tidus. Who happen to be having a lovers' quarrel while Sin runs off like Godzilla I suppose.
At this point Kurugum tells Chuami they will have to part because he has to go with Yuna, that Chuami won't understand because she's not a summoner. Chuami is confused, throws her hands up and tells him to do what he wants.
Chuami heads back to Besaid. Tidus also goes, to ask Lulu about the new guy that Yuna likes. Lulu tells him to go find the guy himself.
At the beach, Chuami wonders aloud where the summoners are; Tidus answers that they must go 'there' (I think he's implying Zanarkand?). Chuami asks him if he's okay with being dumped for that, to which Tidus replies, "We made a promise to be together forever."
Chuami thinks he's full of shit, but doesn't say anything because Tidus is clearly doing a really poor job of hiding his pained face.
At the end, in a stadium setting most likely (from the sounds of crowds and cheering), Yuna promises the people she will defeat Sin.
And this is the artwork of an older Tidus and Yuna.
At this point it is quite possible that we will see an announcement next year and the HD Version makes also much more sense now. So what do you guys think? Or do you even want it?
Personally I think it would be interesting to see how they actually continue this story and series^^