The HD Remaster of Final Fantasy X and X-2 contains a bonus half-hour audio drama written by series wordsmith Kasushige Nojima, and going by this tease it delves into the events following X-2.
The audio episode also feature new characters and voices, but most importantly, it features Tidus' name pronounced in its technically-correct-but-in-reality-just-plain-wrong way. You'll always be Tie-dus to us, Tidus.
Square Enix also confirmed the Remasters feature over 60 "rearranged and optimized" tracks from the FFX soundtrack. That's lovely and all, but the one thing we're still waiting on is a date; both remasters are scheduled to arrive on PS3 and Vita later this year.