Well let's see. They'll need some sort of algorithm to translate the stat-blocks, for starters. Maybe attacks given as a bonus, a THAC0, & a fighter level? A module ported into OD&D would need illustrations that look like a child's crayon drawing, perhaps to be supplied by the children of
WotC employees. The same space would convert to a romance-novel cover painting when viewed as AD&D 2nd Edition. Power gaming would also be an issue. Gandalf was only a 5th-level magic user to the old school, while other editions should be munchkined-out accordingly. What happens when an evil gnoll ranger written for
3e is ported to
1e? Does it become a neutral human fighter? We'd also need to have the paragraphs of a text randomly scrambled for the proper feel of OD&D editing.