At first, I had to consider which selection it might be, given the elimination of the First Blade option. Therefore, my first thought is most probably correct.
would be more help if there were no ‘something else’ option 
That’s evil (normal) zantai for you…
Voted “something else” as I’m still holding out hope for a Paladin/Templar/Cleric type character.
But with a different name Kappa
I’m pretty sure it’s going to be Deathmark.
You mean those riflemen the Black Legion uses?
They use crossbows too. 
But yes, Deathmarks Valar, Kadris, and Harra would have been characters you met during your travels. Here is my rationale behind this pick: http://www.grimdawn.com/forums/showpost.php?p=458612&postcount=6
Oh yeah. Those three guys in Pine Barrens. Yeah could be. I didn’t add them to the poll since their specialty (ranged) is already being added (Inquisitor). But it could be the 8th one
I voted for the necromancer. Because I think that the 8th mastery will be a true necromancer in combination whith occultist mastery. Only suppositions xD.
My guess is on something else as the necro seems too obvious
Feel 90% confident it is necro, but there are some compelling thoughts that it might be shield maiden or combat medic. I just think necro fills a lot more holes in the masteries than either of the other two atm.
As for someone suggesting it might be a mastery that gets 5 cunning per point… That could very well be inquisitor. I expect a lot of the ranged weapon skills will have pierce as a damage type.
Definitely want a mastery that focus heavily on shields (like Defense from TQ). Soldier has a few skills that requires shields, but that’s barely anything. Also want an hand-to-hand mastery.
Gonna be really dissapointed if it’s a Necromancer. Well, at least i know i won’t play as one mastery if that happens. Wait, i already did played that, it’s called Occultist.
Why I don’t think it’s Deathmark / Myrmidon / Combat Medic / Spirit Guide / Bloodsworn / Shield Maiden etc
The names are just way too fluffy.
Deathmarks and Bloodsworns are basically backgrounds, which is weird to see as an actual class. Yes, you can remind me of Inquisitors being a background as well, and now it’s a confirmed class, but at least it makes sense with Inquisitors - from the lore we know that they are artifact users - it’s passable as their distinct feature. What’s a distinct feature of Deathmarks? They are basically marksmans of Black Legion. And yes, “marksman” is a fine name for a class.
It’s the same issue with Combat Medics - the name is quite complicated. If it was something simple, e.g. a “Mender”, then maybe it would had been my personal favourite.
As for Myrmidons - any reason why they can’t actually be, you know, Soldiers?
Shield Maiden is inconsistent since, you know, we - hold your breath - have an option of actually choosing a male character.
Overall my logic is if I was in game designer’s boots, I would had given a base class a simplest name possible, keeping the more complicated, rarely used words for dual classes. E.g. can you imagine Occulist and Witchblade swapping places? Or Soldier and Warder? Would it make much sense?
Pretty much the reason why Necromancer is most consistent here. Simple name that describes class well - that’s a flag. Necromancers also possess magic that is hard to explain in terms of current base classes - that’s another flag.
The only problem is DV vs Kymon’s choice, and it’s quite a serious one. Unless Crate will do a barrel roll and make DV refuse to let Inquisitors in their ranks as well, or just find a good excuse.
Ofcourse it’s based on statement that “we already know what these classes are called since we met them already in the game”, so I made an assumption that correct word is already present in the game. Would be pretty funny if Crate tells us smth like “Oh, Combat Medics, Spirit Guides etc are actually priests, you didn’t knew?!” some time later
P.S. There’s actually an interesting discussion going on in Misadventure 108 thread.
“The burden of death weighs heavily upon all those who forsake their true name and embody the legacy of the Deathmark, a faceless assassin without mercy.”
The item set seems to suggest otherwise - it’s a title, ritual, and way of life too. If Deathmark were to be the 8th mastery I would think Crate would alter some of the NPC Deathmarks in the game so that they don’t all wield ranged weapons. Or instead call them “Marksman” and leave the Deathmark title for select NPCs.
In terms of theme I think it could focus on physical/pierce ranged damage and TQ-style offensive shield procs, among other things.
I think the 8th class could be something like a Priest, but not one thats all into healing.
necromancer or a Templar? maybe… (voted necromancer)
Archon as Something else.
Cleanse the world of the impure. Incinerate the heretics in righteous fire!
A Necromancer.
But i wish for some kind of Mechanic with steampunk “feel”.
Deathmark it is!