Honestly, IV probably has the best shot of getting a full high end remake of the 16-bit era and frankly most of the series not VII or X. It's an entry that is pretty damn popular in both Japan and abroad, and it's actually the entry that has gotten the most ports and remakes in the series.

Granted, I agree that I would like to see V or VI get updated remakes first, even if neither one will be anything close to the VIIR, one on the scale of the Mana remakes would still be pretty neat. SE keeps teasing them, but I don't see it happening for awhile.