My own suspicion is that they'll be moving even further away from any type of buff synergy between the jobs. SE has been working very hard, for good and for ill, to ensure no dominant meta composition is established as far as raids go. There's good reason for this; back in Stormblood, there was a significant period of time where six jobs were basically hard-locked into a raid due to buff synergy. WAR/NIN/SCH/AST/DRG/BRD were basically "required", leaving only a single tank and dps slot available as an option (which most often went to DRK and SMN respectively). WAR provided a slashing debuff that allowed NIN to skip their debuff combo in favor of their raw dps combo. WAR's debuff also buffed the other tank in the party by boosting their damage. NIN provided TA and aggro manipulation, allowing tanks to skip tank stance in favor of dps stance. AST provided the incredibly powerful Spread Balance buff, for a huge party-wide damage boost, while SCH and DRG both boosted crit rate via Chain Stratagem and Battle Litany. Lastly, BRD provided solid group buffs, including TP and MP refresh, in addition to dealing piercing damage, which allowed them to take advantage of the piercing debuff that DRG provided.
SMN brought a rez and a generic damage buff, so they were usually the preferred caster dps. DRK brought TBN which made it so healers could heal even less when dealing with tank busters and a handful of other mechanics, in addition to DRK being able to benefit from Mage's Ballad MP refresh during downtime, providing them an indirect damage boost.
Now, SMN and DRK weren't hard-locked in like the other six were, so you'd sometimes see RDM and PLD, particularly during prog. WHM was basically locked out of raids once prog was over because WHM was all about fixing mistakes through healing and if you were planning on a clear then healing was going to be kept to a minimum. SAM and BLM had a very tough time because a large portion of the raid community seemed to think that they were useless on account of not providing any meaningful group buffs (SAM gave a slashing debuff as well but WAR was so dominant that you basically never had a group without a WAR in it). MNK was like WHM; strong in prog and when at the lower end of the ilvl for a tier, thanks to how strong Mantra was, but ultimately hamstrung by Brotherhood being physical-only, meaning it had no effect on healer dps.
So in practical terms, MNK and WHM were froze out of raid groups after prog was finished and regular clearing had begun in earnest, while SAM and BLM were basically forgotten outside of friend-based statics. Pugging as a SAM or BLM was an effort in futility, despite the fact that they were the ones who could best take advantage of all those juicy raid buffs. It wasn't until the addition of rDPS on FFlogs that the larger, more idiotic-portion of the raiding playerbase finally understood what should have been obvious to them.
We....don't go to Ravenholmdon't talk about MCH. It worked....and it could work really well too. It just required such insane finesse and a super-low ping to pull it all off that it just wasn't worth it for most people. You also had to be comfortable with triple-weaving and loads of GCD clipping so the truth was most people just didn't bother with the job. It was the rarest job in high-end raiding by a large margin. But if you were into that thing it actually cranked out some pretty insane damage, with stuff like SAM openers pushing 6.5k and MCH openers cracking past 7k. It was just loads easier to get that 6.5k SAM opener than it was to get that 7k+ MCH opener (and SAM was by no means easy back then, what with four viable openers based on Sen usage timing and SkS tier).
So anyway, SE looked at what happened in SB and basically swore a blood oath to never let that happen again. Commendable, as party gatekeeping was a major thing that killed fun in FF11 for lots of people, but given their history, I think we'll see them go down the route of eliminating crit buff synergy altogether so as to ensure any given combination of jobs is equally viable. Whether that will be a good thing or not remains to be seen.