I have no anticipation for other possible limited jobs, given the way that SE handled BLU. As one GFAQs poster put it, "BLU is a sightseeing log that wastes other people's time." Given that this was the case for a supposedly "solo" job, I'd imagine that if they promoted Gambler as a limited job designed specifically for groups then it would end up granting an XP penalty past a certain point if you were completing objectives with a group.