It seems like at the beginning they tried to make each job do their primary roles while at the same time give the ability to enhance or debuff a mob to an extent. Bard seemed to have more of a larger AoE ability than the rest. I stopped bard in 1.0 but am trying to pick it up again.
It seems a bit messy but I think they have two options to do things with. One is to increase the enfeeblement and party enhancing abilities of the other jobs to continue along the lines of support for each job/class. Or create that extra slot and add in a support role with BRD and MCH enhancing support while supplying some DPS. It would mean an extra party slot. I only say that because I've gotten into very very rare parties where we had a 5th member..and we rolled with it. I'm not on my PC at home but I sure hope I can find it, I took a picture.
I think either would be an okay idea, but I think the first option would be the easiest. For example, looking at Lancer/DRG, they could take Feint and make it off global, reduce the potency and increase the duration of slow. Increase Keen Flurry to a party AoE, it wouldn't be major but for an add phase parrying some type of HP would be interesting. Then they have Battle Litany which is wonderful in itself.
Then again if they do something like a DPS / Support class slot, they could easily do a skill tree like others suggested to an extent but maybe in terms of Merit Points so they can enhance their abilities as needed. Maybe Enhanced Ballad to give also an AoE magic accuracy buff.
I loved my role as a bard in XI, I enjoyed 1.0 also. I am starting it now in 3.0 and so far I do not see me using any of my songs so much but maybe that's because I eat up a DPS role. If they did add that extra slot but didn't make it pure support..even though Yoshi said there wasn't going to be a dedicated support, wouldn't have to be like XI Bard, could be a lesser DPS hybrid. I'm not sure which would be easier to do now that I'm thinking about it...so much to take in.