I've said it before and I'll say it again: it wouldn't surprise me in the least if a FFVII remake turned-up in some shape or form. Square-Enix is using the multi-platform FFVII Compilation to reach out and grab new fans for the series. So what are these new fans going to want to do once they've become hooked on AC, BC, CC and DC? Play the original game to complete the story, maybe? I'm sure SE don't want them rummaging through bargain bins to find it, so it should be provided for them one way or another.
PS3 remake or just the PSOne original re-released on a PS2 DVD. Who knows. I'd just find it odd if they left new fans hanging like that.