If they ever scrap the class system I would love for the classes to be converted to proper jobs. As for skills they can use the huge arsenal of scrapped skills and changed gamestyles.

For example:
1.) Archer: Reintroduction of charged attacks that was introduced to BRD and MCH in 3.0
2.) Marauders: Reintroduce skills that have been scrapped since 2.0, make them them a dps offensive warrior (DPS)
3.) Arcanist: Give them SMN/SCH scrapped dots.
4.) Rogue: give them rogue/thief flavored skills.
5.) Conjurer: Give them the nature skills maybe convert to DPS.
6.) Gladiator: Give them scrapped paladin skills, maybe in the further make them into a DPS.
7.) Thumaturage: Give them one of BLM many low level play styles as it’s main, perhaps give them dark based skills only.
8.) Puglist: Tank with evasion gameplay, use scrapped skills.
9.) Lancer: Tank, perhaps a mounted tank at higher levels?

While some might be hard to give a alternate play style there is already plenty of scrapped concepts and abilities that can be used for the classes.