Look. I'm bored. You're bored. It's still about a week until the reveals start. So let'S have some fun speculating about things that probably will end up very differently anyways.
Now the new expansion brings us dual-class cards. We also already know all the 10 dual class combinations. Finally, we also know (basically) that there will be a legendary for each dual class combo which will be one of the teachers at the school.
The question is, how will these dual class cards (especially the legendaries) turn out?
Here's what we got so far:
Wand Thief: a basic minion with a Rogue keyword as the activator and a classic Mage staple of discovering a Mage spell (as opposed to just discovering a spell in general). It demonstrates the core philosophy of these cards of being a combination of two class specific previously established mechanics.
Lightning Bloom: Same principle as before, but even more simplified. They took a previously nerfed card (Innervate) and essentially "rebooted" it with the added caveat of Shaman overload. Not so much a strong combination of effects, but rather a very powerful effect (that previously only Druid had access to) balanced by a downside.
Devolving Missiles: a more interesting example of combining a Shaman staple (Evolve/Devolve) and combining it with a recurring Mage theme of damage being applied through split missiles
Shan'do Wildclaw: finally, our first and so far only dual class legendary. She seems to be a rather unique case because instead of having an effect that combines two aspects from both classes she splits them up by utilizing the Druid-only [Hearthstone Card (Choose one) Not Found] keyword. As a result we're getting the Keleseth-esque deck buff that is (currently) clearly intended for midrange Beast Hunter, while the other option is a 3-mana tribal Faceless Manipulator which, while still useful for Hunter, has some rather obvious synergies with the Big Beasts that Druid keeps getting from time to time (such as Winged Guardian). The interesting part is that while there seems to be a clear divide between the options, there is always the option to add support for either class, making it very well executed concept. Basically it confirms that Beasts will be more relevant for these classes in the future.
So...with all that in mind, where will these dual class cards go mechanically and thematically? Let's speculate:
Demon Hunter/Warlock
It's pretty obviously going to be a Demonology focussed class. The teacher will either be a demon or have demon synergy. Similar things will occur with the other cards. I think there's a decent possibility that some sort of Lifesteal-control tool will be among them. Most definitely some sort of Big Demon support for both DH and Warlock. A self-damage synergy card might be in there as well seeing how DH also has the proclivity of ramming their face into spiky things.
Druid/Hunter
As evidenced by the legendary it will most likely be Beast focussed. Maybe there'll be one of the classic Choose One shapeshifters with a possible Hunter twist. Or we just get some allround beasts (both big and small). Either way it's a great opportunity to support the beast archetype for both these classes without having to print lame neutrals
Hunter/Demon Hunter
now the most obvious overlap here would be sm0rc, but I actually think that's not gonna be the case. I think we're gonna be looking at a more token focussed approach. Both Hunter and DH have synergy with small rushing tokens (and Token DH so far has been quite weak...most likely intentionally). Either way I don't believe they'd just push more aggro cards for two classes that already excel at it. THere's also potential for a weapon somewhere in there.
Mage/Shaman
Missiles aren't really much to go by, but it'S fair to assume that there will be an emphasis on spells. Maybe we'll even get some more Burn Spells (which is a major shared theme), some Overload limited card draw, or just some strong AoE. I think it's a safe bet that they'll be referencing the Freeze Shaman meme one more time....but like...good..
Paladin/Warrior
Really hard to evaluate. There's not a lot of overlap between these classes. Handbuff could make a return, but at this point that mechanic just seems dead anyways. A weapon is probably a safe bet. Maybe there'll be more Armor+Healing interactions like Thekal....or maybe Paladin can finally get a proper boardclear by proxy. Big taunts are also a possibility.
Priest/Paladin
aside from the ultra-obvious healing cards there might also be some stat manipulation going on. Perhaps we even see the return of Reborn by way of a substitute teacher from Uldum or something like that. The classes also occasionally share a Deathrattle theme so maybe there's something here. Honestly I feel like there'S too much similarity to really predict how they'll make interesting combinations, but I assume they wouldn't have paired them up if they didn't have a plan.
Rogue/Mage
Equal possibility for burn spells or single target removal. Spell damage with a twist could also be in there. If I had to guess the legendary it would probably involve something about generating extra value. Maybe there'll be some cool stealth minions for mage. The most obvious combo will be a secret though. Both Mage and Rogue need more Secret support and this can easily take care of both...although how a shared secret would look like is anyone's guess.
Shaman/Druid
Lightning Bloom isn't much to go by. I also doubt they'd just print some powerful single-target or AOE removal for Druid (unless it comes with a heavy overload cost). Healing is a shared theme so maybe there's something to find there. There's also shared token strategies between the two. I feel like a Choose One card with two Shaman effects is a likely outcome.
Warlock/Priest
Healing for Warlock. If they don't give us healing for Warlock via this (even if conditional) I'm gonna lose it. Aside from that there's probably going to be some crazy mixed boardwipe and maybe some "kill own stuff and also rez it" shenanigans.
Warrior/Rogue
Aside from the obvious weapons and pirates (perhaps too obvious), this might be a sneaky way for Rogue to get some sort of lifegain. So far nothing suggests that these dual class cards will undermine class weaknesses, but who knows at this point? They can always just come up with a gimmick to limit its usefulness. Either way we should get some sort of BUrgle support through this.
And that's it. That's all I can come up with, but maybe someone else has even more ideas. Feel free to share.