Personally I really like casters, I think you have a case where they have unique upsides and unique down sides, that's way more you can say about any melee really. In terms of "meta" casters and ranged aren't really ever considered for the 4th DPS slot, due to how strong melee is currently, my main hope is they balance out so casters (and phys ranged) can perform slightly better, considering that casters such as BLM/RDM, need way more planning then melees generally speaking.

Hopes for casters in 7.0
Black mage: Just more of the same, personally i think BLM should be performing ever so slightly better then melees (spicy take I know), I really don't think the job needs to change that much.
Red mage: I'd kind of like more Utilities on RDM, Magic barrier was kind of nice, but perhaps something such as a decent healing utility or something that fits with its white mage aspects, I think also adding a little more mobility to RDM, as it can struggle a lot more then people realise, overall the Job is something I enjoy.
Summoner: I hope they make SMN more fun personally, I didn't really like old SMN but new SMN isn't really something I enjoy too much, I think it's main upside generally is how it's way more mobile then any other caster, I think they could likely just build upon what we got on ew and it will be fun for the people who like it, it's certainly a good "starting point" caster job.
New caster?: Hopefully a DOT class, with some similarities with old SMN, while being it's own thing, Hopefully more of a selfish job that doesn't give out a 120 raid buff, Maybe a nice niche Utility but if SMN/RDM keep rez, I think it would be fine without a rez, maybe something a bit more mobile then BLM/RDM but not as mobile as SMN, in general I'm really hoping we get a new Caster and a new tank in 7.0