I do like the idea of a FFX HD remaster. I'm a big proponent of HDing awesome games from last gen, like Resident Evil 4, the god of War series, but I think they could go even farther. Take some of the ideas from even farther back and give them the ol' current-gen polish. Like the much-desired FFVII redo. As much as I'd enjoy an HD X, a remade VII would be just perfect.
What I always found odd about the FFVII remake possibilities is that, from an idea standpoint, everything's there. They don't have to imagine heroes, locales, spells, statistics, Materia, summons, plot twists. This might be a minor concern, but the entire puzzle is right there for the reimagining.
Besides, people can honestly put up the comment of "it's take hundreds of millions of dollars and ten years to remake", while they sit there and make XIII, Versus XIII, Agito XIII(Type-0), XIII-2, and a possible rumored XIII-3, when they could've spent that money and manpower for an awesome current-gen VII, which would sell just as much...no, better, than all of those titles combined. Hell, even if it was PS3-exclusive (it'd almost have to be), I'd break my 360-only stance just to grab a remade VII.