given that they seem to be drawing insperation from each jobs current pvp set up, heres some quick guesses on how each ffxiv existing job is going to "evolve" in 8.0
as a note one of the big things we know is an internal division of the tanking jobs into ones designed as main tanks and ones designed as off tanks. the difference being that at high level content their more suited for those roles, and in general content mains raw tank the damage well off tanks debuff and reduce the damage from the enemy. a pure/barrier healing distinction for tanking basically. aside from the new job being a main tank with pal, every other current tank job is going to be an off tank.
warrior: storms eye is definitely on the table for being cut or consolidated at best, which is probably for the best. aside from that though, i think the warrior is gonna be focused even more on hp regen to offset hp costs for its stronger attacks. in pvp thats how the warrior generally works with ya wanting to keep up your hp nice and high so that your attacks have higher proportional damage. i think other then that, pretty good odds that things like fell cleaver and mythril spin are gonna become parts of special combo attacks that ya spend resource or as noted hp for.
dark knight: if pvp warrior wants to keep its hp high, then pvp dark knight wants to run its hp dangerously low. so i think something like living dead is gonna get a lot more emphasis in the kit now, and that dark knights gonna have more means to ignore damage so it can fight at low hp for longer periods without worrying that a stiff wind will blow it over. i could even see it being where living dead fully imitates its pvp limit break, knocking the dark knight to 1 hp but making them invincible for a lot longer and giving them insane hp regen off of attacks.
gunbreaker: aside from button consolidation i think it'll change the least. maybe some debuffs on enemies from certain attacks to keep with the theme, but its otherwise already in a fairly good spot.
scholar: as we saw with the white mage, the name of the game for healers in 8.0 is more combo potential to fill in time between healing. that means insta cast attacks but casting remaining on their healing, and sch following suit is unquestionable. button consolidation i think will be especially fruitful for scholar as it has a lot of buttons for things that either need to be done in sequence anyways or which do similar things already. in terms of pvp inspirations it could take, assuming it keeps its dot, then being able to apply that on groups of enemys with deployment tactics instead of extending galvanize to the group sounds like a fun possibility. deployable fairy turrets? idk.
astrologian: the ever present question for ast is what to do about tarot, cause it takes up a lot of space but is otherwise pretty core to asts identity. given bard, i think square will keep the full tarot hand but tie more effects and skills into each tarot pull. a party wide buff that combos into an attack or a party wide heal that combos into a mobility buff. cheese like that.
sage: another job in a good place, that will probably benefit from button consolidation but otherwise has a fairly unique flavour to it already. i could see them upping the aggression to keep it the most combat focused healing job but otherwise not much change.
monk: you can bet your ass that its fists getting put into a single button combo is gonna open up a ton of room for monk. well you could argue that its main current gimmick would require an unconsolidated combo, i would actually argue that its current set up could get away with reducing the monks combo down to 4 anyways and still have access to its special attacks. personally the vision i have in mind is having a selection of more specialized attacks that you can input in sequence to end with the super combo. looking to pvp though, i think whats more likely is an emphasis on using the riddles more often and those comboing into more things. flint as a dedicated range attack for monk to poke things with? one can dream.
ninja: the ninjutsu have always been fairly economical to begin with for the amount of stuff they can do in my opinion. ninjas issue is more so that it has such a sprawling nest of other things that dont interact with the ninjutsu in its kit. given how pvp ninja plays, i think the solution square might hit on is having ninjutsu be a state you can enter from the right button combos that alters the rest of your buttons. so you enter the buttons for raiton and your attacks become thunder themed for a few hits, things like that. the ninjutsu is what i expect them to keep around and focus on if nothing else.
samurai: i think it'll end up being kinda like what they showed off with dragoon, where it has a main combo and then resource spending moves that build up the old flower moon snowflake stuff and determines which iatsu you can use. aside from that though i think it's damage negation is gonna be emphasized into more of a counter kind of set up to fit with the samurai theme more.
reaper: given how often i've mispressed it with reaper, i kinda hope that things like guillotine get slotted under an existing button alteration instead of being their own buttons kinda deal. otherwise, absorbing your voidsent i think will be the fulcrum square will focus on for reaper.
viper: instead of having two one button combos, it'll be one one button combo. :> . joking aside, as one of the newer and more original jobs i think its difficult to predict where it might go. maybe it might get snakeskin from the pvp in the main kit but i doubt it, and other then that the future is highly open for where the job could go.
machinist: one of the more constantly shifting jobs, given comments square made though on bard i think machinist will likely remain the raw dps focused ranged job of the current three. other then that though its pvp set up is kinda ass outside of the sniper rifle, and that wouldn't make sense for pve content. maybe it might get more turret variations? i think drill and excavator will probably get bundled in a single combo, well shotgun gets bundled with some sort of aoe special combo from the bio gun and... maybe flamethrower? hell they could throw everyone off balance and go extra hard on machinist gadget references from the rest of the series. definitely one of the jobs to watch though.
dancer: even with consolidation you have enough buttons to play ddr/simon says with dancer so i dont see it changing much otherwise. its fancy lil blade dance from pvp maybe? another one that i dont thinks gonna change much.
black mage: good ol black mage and your incredibly overburdened shoulders. consolidations gonna play hell with black mages playstyle anyways, so i imagine we'll likely see the dreaded combo blm that insufferable people complain about happening happen. if we take some ques from pvp though that does open up some potential fun stuff for the blm though, like counter damage barriers based on astral or umbral, or something like freeze star to the flare star. point being that i imagine to compensate for the "reduced complexity" blm will inevitably be hit with, it'll get some more tools that are based on which alignment it's in.
summoner: once ya consolidate things, that leaves a lot of room left on summoner. my guess is that outside of a complete rework or new mechanics, my honest guess would be that the summons last longer but have longer cooldown periods between them. how or why im not exactly sure, but that is my gut feeling.
red mage: straddling the bare limit of "to many buttons", consolidation gets rid of some of those but it also doesn't leave to much room for trying anything too new with what already exists. i think red mage will either see a major mechanical change, or be one of the more unchanged jobs with no in between.
pictomancer: unlike viper, well pictos new it does have some series history behind it to pull on for new ideas. i think we might end up seeing more of a focus on the sketch mechanic going forward, but otherwise consolidation wont effect it too much so beyond a complete rework i don't think it'll change much either.
the tanks are gonna be the most changed from all of this, well the insufferable blm complexity crowd is gonna be devastated by whatever the fuck happens with it. more news at 11.