Depends what version of the future they'll be using. It could be a '1984' style dystopia dominated by Sentinel & Master Mold in which case the outfits are liable to be of the prison camp fatigues/freedom fighter persuasion. If it's more along the lines of the "Age of Apocalypse" storyline then it'll be more akin to 'Mad Max 2'. Then again it could just be a "normal" future and not require any special costume designs.