I think it would make a nice pairing with red mage as two simultaneously released soloing jobs, one mage, one meleer.
Incorporating it into raiding may be difficult. Thief's asset profile in FFXI was a lot of traits that raiding didn't really want. The concept of thief being a hate controller completely backfired on the job, and ended up being a reason to not invite thieves. Then if they have treasure hunter traits, square will make them pay for that somehow (lower dps again?) and there'll just be a token guild thief again.
It'd be nice if a thief could use combos to unlock steal abilities in fights, and have some raid bosses have an inventory of 3 or 4 stealable items. Doing a successful steal combo results in a final move with 100% chance to steal the item. So like for a bahamut fight, the thief would be dps'ing, and at the beginning of the raid steal a scale, beard, and finally a ring. Then at the end of each combo, instead of stealing, the thief would switch to massive spike damage abilities to bring their DPS up to the rest of the team. You could let like up to 2 thieves do it or something.
I dunno. I just don't want to see thief be hated by the population again.