I think there’s a few niches that could really round out the class roster for this game. For example:
-Disease+Poison: Currently, only NB and DK melee have access to these elements and their uses are very limited. I think it would be wonderful to have a class that could capitalize on these elements.
Ice magic: Exactly why do we not have a class that uses ice magic yet? If an ice magic line were to be introduced into a certain class, I would switch over in a heart beat. It could be possible to introduce a more tactical combo system with ice magic relying on crits.
A proper summoning class. Sorc are not a summoning class despite what the tool tips might say and even their summoning line is flip floppy with its’ passives. Plus, in group PvE and PvP the pets suck. Period. A summoning line needs to be all about the pets and synergizing them with the passives and each other to bring the fantasy to life.
These could easily be part a Necromancer class line.
Nature magic: From what I understand, nature magic was supposed to be a thing but was backed out at the last minute. It would be great to reintroduce it back as its’ own class again
A Hot/Shield based healer: Would be interesting to incorporate these as alternatives to templar healers. Furthermore, it could really introduce more strategic options for PvE and PvP and would allow ZoS to introduce more clever mechanics into PvE as well.
A shape shifting line, possibly short term with both ranged and melee forms. Could also make for a really cool system and just be something different and be explained by the Daedric prince Hircine.
These could easily be part of the mysterious “warden” line.
Now, I know you’re gonna say the trite and completely absurd argument of, “ZOS cannot even balance 4 classes, why add another 1 or 2?”. First things first, MMO’s by their very nature are never going to be 100% balanced and there’s nothing you can do about it unless they give every class the same abilities with the same mechanics and the same numbers. That would be boring so it’s good that each class has their weaknesses and strengths and that not all classes will be capable of doing the same things. Some classes are always gonna be better at burst. That’s okay. Some classes are gonna be better at DPS or ganking or healing. That’s OKAY too.