To make that happen it would mean a bard’s boost must be so powerful that it’s better than using a dps. I find that very unlikely in many respects. In dungeons there would be only 1-2 dps left then doing all the work, and no matter how strong a dps is, soloing trash groups or bosses is no fun; also zero tolerance on this one dying then.
Also the less diversity the more buffs of other classes are missing - so the bard-buff would need to give more than double or tripple dmg for all the remaining dps and be up ALL the time which is never happening because even with several bards it likely would not charge that fast (or be timed that thoroughly…).
Now in raids mechanics don’t allow to go with too many healers, the opposite is the case - talking about hardmode - two bosses are done without healers, on 2 others muskys are preferred, mechanics-wise. Bards are literally solely used to take up one of two healer spots, on one single raid boss, they are generally less (or not at all used) because of the weaker heals, missing shield and missing rez option, so a functional super/dmg boost would be a rather small step to up it’s usability a bit.
And I doubt even this would make raid groups consider changing their setup and use bards more. Ex. pot tank, bards can’t shoot the blue orbs or ads and there’s normally already shamans in the group and tanks who can’t either. And even if it turns out it’s worth having a bard on a no-heals boss, because he CAN replace a full dps - or even do more than him - by up’ing the others dps’es dmg, the whole group would need to wait until the bard’s super is charged, which alone is something groups normally don’t consider, they wanna get through asap.